The Evidence Sprint: Prove Value in 90 Seconds
Most MVPs fail before they launch.
Not because the idea is bad. Not because the team is incompetent. But because it takes 3 months to build and 3 seconds to realize it's not what the client needed.
The Evidence Sprint solves this: working demo + quantified delta in 2-5 days.
The Problem with Traditional MVPs
The term "MVP" has lost all meaning. Here's what it's become:
"Minimum Viable Product" in practice:
- 12 weeks of development
- 47 features (because "we need X to be viable")
- Launch day: clients try it, realize it's not what they wanted
- Total waste: 12 weeks, $50K-$150K
Why MVPs Take So Long
1. Feature Creep
- "We need user auth to be viable"
- "We need notifications to be viable"
- "We need analytics to be viable"
2. No Forcing Function
- If you have 3 months, you'll use 3 months
- Parkinson's Law: work expands to fill time
- No pressure to prioritize ruthlessly
3. No Quantified Success Criteria
- "Let's build it and see if users like it"
- How do you measure "like"?
- When do you know if it's working?
The Evidence Sprint Approach
Instead of building a minimum viable product, we build a minimum viable proof.
Working Demo (≤90 seconds)
Not a mockup. Not a prototype. A working implementation you can use.
- If you can't demo it in 90 seconds, is it focused enough?
- If the value isn't obvious in 90 seconds, will users stick around?
Quantified Delta
Not "it's faster" but how much faster.
Not "it's simpler" but how many fewer steps.
Tag + Proof Entry
Tag the work: evidence-sprint_<milestone>_<date>
- AC.md (what we're proving)
- DEMO.md (where to see it working)
- DELTA.md (quantified improvements)
Real Example: OTP Signup
Client need: Passwordless authentication, fast.
Traditional MVP approach:
Evidence Sprint approach:
Co-write AC.md
# AC.md: OTP Signup Evidence Sprint ## Functional Criteria 1. User enters email, receives OTP 2. User submits OTP, authenticates 3. Session persists 30 days ## Non-Functional Criteria - p95 latency: < 300ms (full flow) - Steps to complete: ≤ 3 - Mobile responsive ## Verification npm run acceptance:signup
Build minimal proof
- Email OTP delivery (no SMS, no backup codes, no recovery)
- Simple session management (no OAuth, no SSO)
- Basic error handling (no edge cases yet)
Generate delta
| Metric | Before | After | Change |
|---|---|---|---|
| p95 latency | 1200ms | 280ms | ↓77% |
| Steps to complete | 7 | 3 | ↓57% |
| Forgot password flow | 3 steps | eliminated | - |
| Mobile conversion | 42% | 68% | ↑62% |
Ship demo + tag
demo.scopelock.ai/otp-signupevidence-sprint_otp-signup_2025-11-02/proof/evidence-sprint_otp-signup_2025-11-02The 90-Second Demo Rule
Why ≤90 seconds?
1. Forces Focus
If you can't show value in 90 seconds, you're building too much.
Open page → Enter email → Receive OTP → Submit → Authenticated
Explain architecture → Show database schema → Walk through 5 features
2. Matches Real User Attention
Users don't give you 10 minutes to "show potential."
They give you 30 seconds to prove value or they bounce.
3. Enables Decision-Making
In 90 seconds, a client can decide:
All outcomes are valuable. Finding out in 5 days vs 5 months is the difference.
Quantified Deltas: Not Feelings, Numbers
Every DELTA.md must have measurable before/after.
❌ Bad Delta
## What Changed - Made it faster - Simplified the flow - Improved UX
✅ Good Delta
## Performance - p95 latency: 1200ms → 280ms (↓77%) - Time to first interaction: 850ms → 190ms (↓78%) ## Usability - Steps to complete: 7 → 3 (↓57%) - Form fields: 12 → 2 (↓83%) ## Conversion - Mobile signup rate: 42% → 68% (↑62%) - Completion rate: 54% → 81% (↑50%)
Evidence Sprint vs Discovery Phase
Most agencies sell a "discovery phase" before building. Here's the difference:
| Aspect | Discovery Phase | Evidence Sprint |
|---|---|---|
| Deliverable | Document | Working demo |
| Timeline | 2-4 weeks | 2-5 days |
| Output | "Here's what we'll build" | "Here's what we built" |
| Cost | $5K-$15K | $3K-$6K |
| Risk | Still don't know if it works | You've seen it working |
When to Use Evidence Sprint
✅ Perfect For
- Validating new ideas: "Will OTP signup work for our users?"
- De-risking big projects: "Can we hit <300ms p95 before committing?"
- Rapid prototyping: "We need a working demo for investors by Friday"
- Proof before commitment: "Show me it works before I approve the full build"
❌ Not Ideal For
- Well-defined features: If you know exactly what you want and have full specs, go straight to AC green
- Pure research: If you're exploring problem space without building, use a different approach
- Long-term maintenance: Evidence Sprints prove value, not operational readiness
How to Apply This
If You're a Founder
Before committing to a 3-month build, ask your developer:
- Working demo in 2-5 days
- Quantified delta (numbers, not feelings)
- Clear path: iterate, proceed to AC green, or pivot
If You're a Developer
Instead of quoting 8 weeks for an MVP:
- Minimal proof of concept (working, not polished)
- DELTA.md with real numbers
- Demo link clients can share with stakeholders
Three Common Questions
"Isn't this just a prototype?"
No. Prototypes are fake (Figma mockups, clickable demos).
Evidence Sprints are working implementations:
- Real database
- Real auth
- Real performance metrics
- Real code that becomes production
"What if the Evidence Sprint proves it won't work?"
That's success.
You spent 5 days and $3K-$6K to learn this won't work.
Alternative: Spend 12 weeks and $80K to learn the same thing.
"Do you always do Evidence Sprints?"
No. If requirements are crystal clear and risk is low, we skip straight to AC green.
Evidence Sprints are for validation and de-risking, not for every build.
The Math That Matters
Traditional MVP
Evidence Sprint
The difference:
What's Next?
At ScopeLock, we start high-risk projects with Evidence Sprints.