Short answer: One week is the right sprint length when AI is doing the planning + story breakdown + AC authoring for you. The traditional 2-week sprint defaults are calibrated to slow, manual planning. AI changes the math.

Below is the reasoning, the team-size adjustments, and the anti-patterns to watch.

Why 2-week sprints became standard

The 2-week sprint became dominant in the late 2000s for a real reason: planning meetings + story refinement + retros took 6-8 hours per sprint. Spreading that overhead across 80 working hours kept it under 10% of team capacity. A 1-week sprint with the same overhead would have eaten 20% of every week — too much.

The choice was: spend 10% of every two weeks on planning, or shorten the loops at the cost of doubling the planning tax. Most teams picked 2-week.

Why AI changes the math

AI sprint planning cuts the meeting overhead by ~60% (per Stride telemetry across 400 sprints). Specifically:

Capacity computation: 15 min → 0 (AI does it before the meeting)
Story breakdown from PRD: 60-90 min → 5-10 min (review the AI's output)
AC authoring: 8 min/story → 2 min/story
Sizing debates: 3-5 min/story → 60-90 sec/story

For a typical 12-story sprint, total planning overhead drops from ~3 hours to ~1 hour. That changes the calculus.

Sprint length	Manual overhead	AI-assisted overhead
1 week	6-8 hr (~15% of week)	2-3 hr (~5%)
2 weeks	6-8 hr (~7%)	2-3 hr (~3%)

Manual planning made 1-week sprints expensive (15% of every week is a lot). AI-assisted planning makes them cheap (5% is comparable to what 2-week sprints used to cost).

Why 1-week wins (when AI is doing the heavy lifting)

Three reasons.

Faster feedback loops. A 1-week sprint ends 4x faster than a monthly milestone. Wrong direction caught in week 2 instead of month 3.

Smaller scope-creep blast radius. Mid-sprint scope changes affect 1 week of work, not 2. The team can absorb a small re-plan without losing the goal.

More frequent retrospectives. Retros that produce real change need momentum — 52 retros a year build a sharper team than 26. The cost of the extra retro is small with AI handling the data analysis.

The exception: teams where individual stories genuinely take a week to complete (deep refactors, complex integrations, regulatory work). For those teams, 1-week sprints starve the team — half the stories don't close. Stay at 2 weeks until the work units genuinely fit a 1-week cadence.

Team-size adjustments

1-3 engineers: Skip sprints entirely. Use a continuous flow + weekly checkin. The overhead-to-throughput ratio of any sprint cadence isn't worth it at this scale.

4-10 engineers: 1-week sprints are the sweet spot when AI is involved. Fast feedback loops + low planning tax.

11-25 engineers: 1-week sprints work; 2-week is also defensible if cross-team coordination needs more buffer. Don't go longer than 2.

26-100+ engineers: 2-week sprints synchronised across teams. The coordination cost of weekly sync between 5 teams is non-trivial, and AI doesn't fix that part. Go to monthly only if you're shipping infrequent, large changes (regulated industries, hardware-coupled software).

What changes inside the sprint at 1-week cadence

A 1-week sprint without process adjustments looks identical to half a 2-week sprint — same ceremonies, same friction, just compressed. That's worse than 2-week.

The adjustments that make 1-week work:

Lighter standups. 5 minutes max, 3 days a week (not 5). The "what blockers?" conversation is the only real signal in a 1-week sprint.
Mid-sprint demos at end-of-day 3. Quick "show me what's working" check-in. Catches "wrong path" 4 days into the sprint, not 8.
Tighter story sizing. 1-week sprints should have stories sized 1-5 points (no 8s, definitely no 13s). If your team can't size that small, you're not ready for 1-week.
No mid-sprint adds. A 1-week sprint is too short to absorb scope changes. Adds wait for the next sprint. This is easier to enforce than in 2-week because the next sprint is 3-4 days away.
Retros at the same depth. Some teams cut retros to 15 min for weekly sprints. Don't. The retro is what makes the weekly cadence pay off. Keep at 30-45 min.

Anti-patterns

Sprint length as productivity theater. "Let's do 3-day sprints so we ship more!" No. 3-day sprints make the planning overhead unaffordable + force stories sized at 1 point or smaller, which is unreliable estimation territory. 1-week is the floor for sprints.

Sprint length without AI. Going to 1-week sprints without AI sprint planning + AC generation + capacity automation means the planning overhead doubles relative to a 2-week sprint. You'll burn out the team in a quarter.

Sprint length disagreement within a team. Half the team wants 1-week, half wants 2-week. Pick one. Two weeks is a fine default if the team is split — better than fighting about it every other week.

Sprint length to match management cadence. Some teams adopt 4-week sprints because finance/leadership tracks things monthly. Resist. The internal sprint cadence should match what the team needs; external reporting can summarise multiple sprints.

What about no-sprint flow (Kanban)?

A reasonable alternative when:

Work units are wildly variable in size (some 1-hour, some 5-day)
Interrupt-driven work is the norm (operations, on-call-heavy teams)
The team is mature enough to self-manage flow without sprint anchors

Kanban-with-AI is roughly equivalent to 1-week-sprints-with-AI in throughput, but the social dynamics are different. Sprints create natural retrospective moments; Kanban requires the team to manufacture them. If your team is disciplined, Kanban is fine. If you need the retro anchor, stay on weekly sprints.

The math behind realistic sprint capacity — relevant whether you're at 1-week or 2-week cadence.

Sprint capacity planning in detail

How long should a sprint be when using AI to write stories?