The research behind Day0
Figures are as reported by each source. Vendor data is labeled. Re-verified before launch.
| Finding | Figure | Source |
|---|---|---|
| Output grew far more than delivery | Lines of code 8.4×, commits up to 3.4×, releases about 1.3×, no detectable change in usage so far | [1][2] |
| Review became the queue | Median PR review time +441.5%; PRs merged with no review +31.3% Vendor data, correlational | [3] |
| Problems grew faster than output | Incidents per PR +242.7%; deployments per week −11.7% Vendor data | [3] |
| Testing is overloaded | Time in QA +300.6% Vendor data | [5] |
| Even AI labs hit the wall | CI job volume up 25× in six months; writing code “no longer the constraint” | [6] |
| Coding is a minority of the work | Writing and testing code is 25–35% of idea-to-launch time | [7] |
| Redesign beats tools | Assistants alone 10–15% gains; with end-to-end redesign 25–30% | [7] |
| Feeling fast is not being fast | Experts believed AI made them 20% faster; measured 19% slower | [8] |
| Trust depends on checking | 48% trust AI output when they can easily verify it; 78.7% say source attribution matters | [9][10] |
| Review work is growing | 67% of developers spend more time reviewing AI-generated code | [11] |
| A low-risk lane works at scale | 331,000+ changes landed; reverted at a third of the rate, incidents at a fiftieth, median time in review −35% The lane selected low-risk changes, so not causal | [12] |
| Risk can be predicted | Flagging 10% of changes caught 60% of incident-causing ones | [13] |
| Throughput without review capacity | PRs per developer 2.09×; total PRs 3.1× while reviewers grew 1.5×; thorough human review fell from about 39% to 21% | [14] |
| Agent projects fail on value and control | Over 40% of agentic AI projects predicted to be cancelled by end of 2027 | [15] |
| Shipping is not adoption | 80% of features are rarely or never used; customers with 25+ in-app guides used 25% more features daily | [16] |
Sources
- 1
Demirer, Musolff and Yang, Writing Code vs. Shipping Code, NBER working paper 35275 (2026)
https://ideas.repec.org/p/nbr/nberwo/35275.html - 2
VoxEU column on the same study
https://cepr.org/voxeu/columns/writing-code-versus-shipping-code-productivity-effects-across-generations-ai-coding - 3
Faros AI, AI Engineering Report 2026 (vendor data)
https://www.faros.ai/research/ai-acceleration-whiplash - 4
Faros AI, The AI Productivity Paradox (2025, vendor data)
https://www.faros.ai/blog/ai-software-engineering - 5
Faros AI, The Speed Trap (Q3 2026, vendor data)
https://www.faros.ai/blog/ai-speed-trap-takeaways - 6
Anthropic, Agentic coding is straining CI (September 2026)
https://claude.com/blog/agentic-coding-is-straining-ci-heres-how-we-scaled-test-impact-analysis-at-anthropic - 7
- 8
METR, developer productivity study and 2026 design update
https://metr.org/blog/2026-02-24-uplift-update/ - 9
Stack Overflow Developer Survey 2026, via Visual Studio Magazine
https://visualstudiomagazine.com/articles/2026/10/06/stack-overflow-2026-survey-vs-code-leads-visual-studio-takes-third.aspx - 10
Stack Overflow Developer Survey 2026, via IT Brief
https://itbrief.co.uk/story/stack-overflow-survey-finds-developers-wary-of-ai-tools - 11
BairesDev Dev Barometer Q3 2026, via IT Brief
https://itbrief.co.uk/story/ai-coding-tools-shift-developers-towards-review-work - 12
Meta, Automating Low-Risk Code Review at Meta: RADAR (2026)
https://arxiv.org/pdf/2605.30208 - 13
- 14
He et al., AI Writes Faster Than Humans Can Review (2026)
https://arxiv.org/pdf/2607.01904 - 15
Gartner prediction on agentic AI project cancellations, via W.Media
https://w.media/over-40-percent-of-agentic-ai-projects-could-face-the-axe-by-end-of-2027-gartner/ - 16
Pendo, 2019 Feature Adoption Report
https://www.pendo.io/resources/the-2019-feature-adoption-report/ - 17
DORA AI Capabilities Model (Google Cloud)
https://cloud.google.com/blog/products/ai-machine-learning/from-adoption-to-impact-putting-the-dora-ai-capabilities-model-to-work/ - 18
Meta, mapping tribal knowledge into context files (2026)
https://engineering.fb.com/2026/04/06/developer-tools/how-meta-used-ai-to-map-tribal-knowledge-in-large-scale-data-pipelines/ - 19
DX, State of AI Impact in Engineering, Q2 2026
https://getdx.com/news/dx-releases-q2-2026-state-of-ai-impact-in-engineering-report/ - 20
Atlassian, State of Developer Experience 2025
https://www.atlassian.com/blog/developer/developer-experience-report-2025