TL;DR: In both September 2026 tests where we compared time and cost, GPT-5.6 Luna was the quicker or more economical finish and DeepSeek V4.1 Flash built the richer app. On the Sep 30, 2026 intake form both saved every answer and both photos, and both follow-up changes went live. Luna's public assistant named a child to a visitor, and Flash's build ran past the 15-minute limit. Try the same kind of request in Taskade Genesis.
What TSK-1 Found
Each test sends one request, word for word, to every model in it. We open every app, use it the way a customer would, and read what it saved back before we record a result. These are the tests that both models took.
| Test | Model | What the app did | Result |
|---|---|---|---|
| Family intake form, Sep 30, 2026 | DeepSeek V4.1 Flash | Saved every answer and both photos on a two-page form, and the follow-up change landed. The build ran past the 15-minute limit. | Works, with gaps |
| Family intake form, Sep 30, 2026 | GPT-5.6 Luna | The most economical complete build: every answer and both photos saved. Its public assistant told a visitor a child's name. | Works, with gaps |
| Match tracker, Sep 22, 2026 | DeepSeek V4.1 Flash | Three pages, and its coaching automation wrote a note into the first match logged. | Works |
| Match tracker, Sep 22, 2026 | GPT-5.6 Luna | The fastest and most economical complete build, in 8 minutes 19 seconds. A match saved from the app came back with all eight details. | Works |
| Recipe box, Sep 19, 2026 | DeepSeek V4.1 Flash | A printed cookbook with 13 recipes across four pages, and both automations live. | Works |
| Recipe box, Sep 19, 2026 | GPT-5.6 Luna | A warm printed cookbook in light and dark, with every page loading cleanly. | Works |
One build per model in each test. See the full evidence at /tsk/deepseek, /tsk/gpt, and the TSK-1 hub.
The Family Intake Form (Sep 30, 2026)
Both models saved everything a parent sent. The request came from a real customer: parents fill in a form on their phone with two to four photos, and the teacher sees every family on one page. Both forms saved every answer and both photos, and both added the new teacher question when we asked for it.
GPT-5.6 Luna got there as the most economical complete build of the test. Its miss was about privacy, not data: its public class assistant told an anonymous visitor a child's name from a saved form. An owner has to close that before the app goes out.
DeepSeek V4.1 Flash built a two-page form, and its alert automation ran twice. The build ran past our 15-minute test limit before it finished, although the app it wrote worked and its follow-up change went live.
The Match Tracker (Sep 22, 2026)
This is the cleanest picture of the trade-off. One player logs each game with hero, result and notes, and a dashboard shows win rate and streaks.
GPT-5.6 Luna built a two-page tracker in 8 minutes 19 seconds, the fastest and most economical complete build of the test. A match saved from the app came back with all eight details in place.
DeepSeek V4.1 Flash built three pages, and its coaching automation ran on the first match logged. About six minutes later it wrote a coaching note back into that match. Luna's app was the quicker, leaner finish. Flash's app did more on its own once someone used it.
The Recipe Box (Sep 19, 2026)
In the recipe-box test, seven models built a recipe box and every one came out as a warm printed cookbook. Luna's rendered cleanly in light and dark, with every page loading. Flash's held 13 recipes across four pages, with both automations live.
Other September results are not head-to-heads, because the two models did not build the same request, but they point the same way. DeepSeek V4.1 Flash built the richest sales CRM of its test, six pages with a scoring automation that scored all 7 sample leads. GPT-5.6 Luna built a fleet-inspection app with both weekly automations live in 7 minutes 18 seconds, and passed all five follow-up-edit tests on its habit tracker.
Choose DeepSeek V4.1 Flash If…
- You want more app per request. It built three pages where Luna built two on the match tracker, and a four-page cookbook with both automations live.
- Automations have to run on real entries. Its coaching automation wrote a note into the first match logged, and its intake alert automation ran twice.
- You can give the build more time. Its intake build ran past the 15-minute limit, and the app it wrote still saved everything.
Choose GPT-5.6 Luna If…
- Speed matters. It was the fastest complete build of the match-tracker test, at 8 minutes 19 seconds.
- Cost matters. It was the most economical complete build in both the match-tracker and the intake-form tests.
- The brief is detailed. Luna is the most faithful model we have tested. It has reproduced all 32 questions of a real customer's sign-up form word for word, and it passed every September follow-up-edit test.
- You will review the public assistant before sharing. Its intake app was complete, and the one fix it needed was in what its public assistant would say.
The Taskade Angle: Route, Don't Standardize
Taskade routes across frontier models from top AI labs inside one workspace, and you set the model per agent or per automation step. A fast first build on GPT-5.6 Luna and a richer automation pass on DeepSeek V4.1 Flash can share one app, one set of projects, and one memory. Leave a step on TSK-1 Auto and Taskade picks the model for you.
Final Word: The Quick Finish vs the Richer App
GPT-5.6 Luna and DeepSeek V4.1 Flash took the same requests three times in September 2026, and the pattern held. Luna was the fast, economical finish that sticks to the brief, with one privacy miss to fix on the intake form. Flash was the richer app with automations that ran, and it needed more time. One build per model per test, so treat it as a direction. We will add builds as new tests run.
▲ Memory feeds Intelligence. ■ Intelligence triggers Execution. ● Execution creates Memory. Two economical models. One workspace.
Build your own app in Taskade Genesis →
Related reading
- DeepSeek vs ChatGPT - The two families across every test.
- GPT-6.1 Sol vs Claude Opus 5.5 - The newest models on the same intake form.
- TSK-1 hub - The complete model test dataset.
