Scaling Engineering Teams: Lessons from the Trenches

Scaling an engineering team is one of the hardest challenges a CTO faces. What works at 5 people breaks at 15. What works at 15 people breaks at 50. Here's what I learned scaling teams through these inflection points.

The Growth Stages

Every team goes through predictable phases, each with unique challenges:

Stage 1: The Startup Team (5-10 people)

Characteristics:

• Everyone knows everything
• Direct communication works
• Flat structure with minimal process
• High autonomy, low coordination overhead

What works:

• Daily standups
• Shared Slack channels
• All-hands demos
• Informal code reviews

What breaks first:

• Information sharing (people miss important updates)
• Context (new hires feel lost)
• Decision-making (too many cooks)

Stage 2: The Scale-Up Team (10-25 people)

Characteristics:

• Silos start forming
• Communication breaks down
• Process becomes necessary
• Technical debt accumulates

What you need:

• Team structure (pods/squads)
• Engineering managers
• Documented practices
• Clear ownership boundaries

Common mistakes:

• Adding process too slowly (chaos)
• Adding process too quickly (bureaucracy)
• Promoting IC to manager without support
• Ignoring culture as you hire

Stage 3: The Growth-Stage Team (25-50+ people)

Characteristics:

• Multiple teams with different contexts
• Cross-team coordination required
• Specialized roles emerge
• Culture dilution risk

What you need:

• Organization structure with clear reporting
• Staff+ engineers for technical leadership
• Platform teams
• Standardized tooling and practices

Key Lessons Learned

1. Hire for the Next Stage, Not the Current One

The mistake: Hiring people who fit today's needs perfectly but can't scale with you.

The fix:

• Hire senior people before you think you need them
• Look for people who've been through your next stage
• Balance for diverse skill levels (not all senior, not all junior)

The ratio that worked for me:

• 20% senior+ (mentors and architects)
• 50% mid-level (workhorses)
• 30% junior (fresh perspectives, great ROI with mentoring)

2. Structure Follows Strategy

Don't copy another company's org chart. Structure your team based on your specific goals.

Common structures:

Feature teams:

• Organized around product features
• Good for: Customer-facing product velocity
• Risk: Neglecting infrastructure

Platform teams:

• Organized around technical capabilities
• Good for: Building scalable foundations
• Risk: Disconnection from customer needs

Hybrid (my preference):

• Feature teams with embedded platform specialists
• Rotating platform team membership
• Shared services team for common infrastructure

The rule: Reorganize thoughtfully, but don't reorganize constantly. Aim for stability of at least 6-12 months.

3. Communication Scales Quadratically, Solve It Early

With 5 people, you have 10 communication paths. With 50, you have 1,225.

Solutions that worked:

Written culture:

• Document decisions (use ADRs)
• Write design docs before coding
• Maintain updated runbooks
• Use RFCs for major changes

Structured meetings:

• Weekly team leads sync
• Monthly all-hands with Q&A
• Quarterly planning sessions
• Skip-level 1-on-1s

Information radiators:

• Shared Slack channels for announcements
• Wiki for evergreen knowledge
• Weekly email updates from leadership
• Public roadmap

4. Maintain Culture Through Intentional Practices

Culture doesn't scale automatically—it gets diluted without deliberate effort.

What preserved culture for us:

Hiring:

• Values-based interview questions
• Culture fit as a hiring bar (but define it clearly)
• Diverse interview panels
• Consistent onboarding

Rituals:

• Weekly demo days (show what you built)
• Monthly team lunches (budget for it)
• Quarterly off-sites (team building + strategy)
• Annual hackathons

Recognition:

• Public shoutouts in all-hands
• Peer recognition programs
• Clear promotion criteria
• Celebrating failures (blameless postmortems)

5. Create Leverage Through Engineering Managers

The inflection point: Around 8-12 engineers, you need your first EM.

What I got wrong initially:

• Promoted the best IC to manager (wrong criteria)
• Expected them to figure it out alone (no training)
• Measured them by code output (wrong metric)

What works:

• Hire or promote for people skills + technical credibility
• Invest in manager training (courses, coaches, books)
• Measure by team output and satisfaction
• Maintain IC track (not everyone wants to manage)

The EM role:

• 1-on-1s with every report (weekly)
• Performance management and feedback
• Team health and culture
• Roadblock removal
• Hiring and onboarding

6. Don't Neglect Technical Excellence

It's easy to let quality slip when moving fast.

Non-negotiables:

• Code review for all changes
• Automated testing (unit + integration)
• CI/CD pipeline
• Monitoring and alerting
• Regular tech debt sprints (10-20% of capacity)

The staff engineer role: As you scale, create IC leadership roles focused on technical excellence, not management.

7. Build Systems for Knowledge Transfer

The problem: Key knowledge locked in individual heads.

Solutions:

Documentation:

• Architecture decision records
• System diagrams (C4 model works well)
• Onboarding guides
• Runbooks for critical systems

Pairing and rotation:

• Pair programming on complex features
• Rotate on-call responsibilities
• Cross-team shadowing
• Knowledge-sharing sessions

Code as documentation:

• Self-documenting code
• Comprehensive README files
• In-code architecture diagrams
• OpenAPI specs for APIs

8. Planning Becomes More Important

At 5 people, you can pivot daily. At 50, you need more structure.

Quarterly planning:

• Top-down goals from leadership
• Bottom-up estimates from teams
• Buffer time (things take longer than expected)
• Explicit trade-offs discussed

The planning rule: Spend time planning proportional to team size. At 50 people, invest 2-4 weeks per quarter in planning.

The Biggest Mistakes I Made

1. Scaling Too Fast

We doubled the team in 3 months. It nearly broke us.

Lesson: Aim for 30-50% growth per year maximum. Quality over speed.

2. Not Investing in Management Early Enough

I tried to manage 15 people directly. Everyone suffered.

Lesson: Hire/develop managers at 8-10 reports, not 15+.

3. Ignoring the Middle

Focused on senior hiring and junior training, neglected mid-level engineers.

Lesson: Mid-level engineers are your multipliers. Invest in growing them.

4. Copying Others' Playbooks

Read about Spotify squads, tried to implement exactly. Failed.

Lesson: Understand principles, adapt to your context.

Practical Action Plan

If You're at 5-10 People:

1. Document your core values now
2. Create your first hiring scorecard
3. Start writing things down
4. Implement code review process

If You're at 10-25 People:

1. Hire or develop your first EM
2. Define team structure
3. Implement RFC process
4. Create career ladders
5. Start quarterly planning

If You're at 25-50+ People:

1. Establish clear org structure
2. Create staff engineer positions
3. Implement formal performance process
4. Build platform teams
5. Invest heavily in documentation and tooling

Final Thoughts

Scaling is hard because what got you here won't get you there. You must continually evolve your practices, structure, and even yourself as a leader.

The good news: These challenges are well-understood. Many have walked this path before. Learn from their mistakes (and mine).

The better news: A well-scaled team is a joy to lead. The systems you build, the culture you maintain, the people you develop—these compound over time into something remarkable.

Remember: You're not just scaling a team. You're building an organization that can outlast you.

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What's your biggest scaling challenge right now? What stage are you at, and what's breaking?