When have I researched an idea enough to take the next step?
Research can turn up similar work and real constraints. It can also become a comfortable place to hide when the next step is a decision. Decide what your preliminary research needs to answer, set a review point, and treat that point as the time to decide.
The imagination session's emphasis on execution makes this worth a look. Start by listing the questions your research must answer, and sort the facts you need before proceeding from the details you can pick up during a small, permitted test.
At the review point, summarize what's known, what's still uncertain, and whether the uncertainty changes your next commitment. I'd skip the extra search just because a tool can produce more material.
The stakes change the rule
If a missing answer involves rights, safety, cost or a consequential claim, keep checking or bring in the right specialist. A stopping rule doesn't excuse you from a verification you need.
For lower-stakes creative choices, make the call and save the alternative for later. Research should help you take a better-informed next step. It can't remove every reason the project might disappoint you.
What to try this week
Before your next research session, write down the question it needs to answer and when you'll stop to decide.