Rock Sizing
How to prioritize and plan initiatives.
TL;DR
- Rocks (>2 sprints): Strategic, long-term, maximize impact. Exec decides.
- Pebbles (6-20 days): Tactical, short-term, maximize ROI. PM decides.
- Sand (≤5 days): Immediate, maximize throughput. PM/Dev decides.
Framework
| Rocks | Pebbles | Sand | |
|---|---|---|---|
| Effort | > 2 Sprints | 6-20 days (up to 2 sprints) | ≤ 5 days |
| Maximize | Impact | ROI | Throughput |
| Outlook | Long-term: Winning over the next few years | Short-term: Winning over the next few months | Immediate: Short tasks that just need to be done |
| Scope | Strategic | Tactical | Any |
| How Decide | Deliberate | Analytical | Intuitive |
| Role of Exec | Decider | Observer | None |
| Role of PM | Driver | Decider | Decider (engage devs) |
| Beware | Insufficient impact | Over-estimating ROI | Over-thinking / over-planning |
How to Prioritize
- Start with Rocks: What are the 1-3 strategic bets for the quarter?
- Fill with Pebbles: What tactical wins support the rocks?
- Leave room for Sand: Reserve 20-30% capacity for quick wins and urgent fixes.
Example Quarter:
- Rock: Launch payments in 3 new countries (12 weeks)
- Pebbles: Add Apple Pay, optimize checkout flow, integrate fraud detection
- Sand: Fix bugs, update copy, improve error messages
Common Mistakes
Mistake 1: All Rocks, No Pebbles
Team burns out. No quick wins to show progress.
Fix: Balance rocks with pebbles. Ship something every 2 weeks.
Mistake 2: All Sand, No Rocks
Busy but not moving forward strategically.
Fix: Dedicate 50%+ capacity to rocks and pebbles.
Mistake 3: Rocks Without Milestones
Can't measure progress. Team loses motivation.
Fix: Break rocks into 2-sprint epics with clear deliverables.
Related: DRI Responsibilities • DRI Weekly Sync