[philsnow]

> I would put in an honest effort and get 90% of the problem solved, but get denied because my solution wasn't flawless

It's possible that the company stated the take-home work in terms of non-negotiable deliverables, and their baseline for allowing a candidate to move forward is 100% of those, and they prioritize candidates who take initiative and do more work beyond the base requirements.

... not that I would agree with such a process (it biases towards people with more free time, like people with fewer dependents and people who are currently out of a job / underemployed), but it's very possible that this is what you faced.