• 77% of enterprises re-evaluate AI vendors at least every six months, and 29% do so on a rolling basis, per Madrona's survey of 150 buyers.
• 83% of enterprises converted fewer than half their AI pilots to production in the past year; only 1% converted more than three-quarters.
• Microsoft leads AI vendor distribution at 78% paid penetration; Anthropic leads satisfaction with an 8.4 NPS.
• A separate Andreessen Horowitz survey of 50 technical buyers found roughly two-to-one preference for outcome- or credit-based pricing over per-token fees.
• Founders should structure contracts and product roadmaps around a six-month review cycle, not an annual renewal date, when underwriting ARR.

Enterprise contracts no longer buy startups predictable annual recurring revenue. A Madrona Venture Capital survey of 150 senior enterprise decision-makers, published August 13, 2026, found that 77% re-evaluate their AI vendors at least every six months, and 29% do so on a rolling basis with no fixed review cycle. Madrona's report describes a "fast in, fast out" dynamic that breaks the assumption underlying startup valuations for a decade: that a signed enterprise logo locks in years of revenue.

The churn number that resets startup ARR math

The headline figure is vendor re-evaluation cadence, not just win rate. Madrona's survey found 77% of enterprises re-evaluate AI vendors within six months of signing, with 29% treating vendor review as continuous rather than scheduled. For a startup, that means an enterprise logo signed in January is a two-quarter renewal risk, not a multi-year annuity — undercutting the ARR multiples investors have used to price rounds since the AI spending boom began.

Pilots die in procurement, not the demo

Vendor churn compounds a production problem. The same Madrona survey found 83% of enterprises converted fewer than half of their AI pilots into production over the past year, and just 1% pushed more than three-quarters through. Madrona's authors, Rolanda Fu, Matt McIlwain and Vivek Ramaswami, write that "pilots don't die in the demo. They die in the gauntlet of integration, compliance, procurement, and organizational buy-in that comes after" — the exact stage where startup sales teams lose visibility and control.

Microsoft wins distribution, Anthropic wins loyalty

The vendor leaderboard splits along two different axes. Madrona's data puts Microsoft ahead on reach, with 78% paid penetration across the surveyed enterprises, while Anthropic leads on customer satisfaction with a Net Promoter Score of 8.4. For challenger startups, the split is instructive: distribution and loyalty are won separately, and a smaller vendor can defend renewal without matching an incumbent's install base — if it earns the NPS.

Founders are pricing for retention, not usage

A separate Andreessen Horowitz survey of 50 technical AI buyers, published August 27, 2026, found roughly two-to-one preference for pricing tied to delivered work over raw token consumption. a16z partners Tugce Erten and Sarah Wang write that "token pricing pulls the customer conversation toward a cost curve that keeps falling," pushing them to recommend credits or outcome-based fees that survive a vendor's six-month review.

The bet: structure for review cycles, not renewal dates

The operator takeaway is to build contracts and product roadmaps around the review cycle Madrona measured, not the annual renewal date on the invoice. That means shipping visible, attributable wins before the six-month mark and pricing around outcomes a procurement team can defend internally. Startups that treat ARR as locked-in will misprice their own risk; the ones underwriting churn into their model are the ones a Series A investor should actually bet on.