These should not take 10 hours, unless you're learning Rails from scratch or something (some people do this). We've tried different ways of saying "don't spend more than 2 hours on this unless you really want to" and it doesn't always come through.
I don't know what fly's internal processes are, but I suspect the reviewer had to have submitted some bit of internal feedback on each submissions on why they're okaying it or not. A filtered version of it or even a separate candidate specific feedback would be just enough.
I've been at the hiring side of the table for many years and every time we share a handcrafted feedback to interviewees that we have passed on, we always heard back good things. They know we respected their time (and them), even if they don't agree with the particular feedback.
This feedback is not meant for them to get "better" or something. My point is, it could even be 2 hours the candidate spends, the least they deserve is knowing that it was actually looked at.
The submissions that we continue with check a bunch of boxes. The submissions that we pass on don't.
The problem is, we're not hiring people to build to a spec. We want to assess your decisions and ability to go from a basic problem to a first implementation. If we shared the rubric with folks, they'd focus entirely on trying to check the boxes and I don't think we'd get an accurate assessment.
Your point about valuing peoples' time is important, though. We have not yet found the right balance for everyone.
You could have told the candidate that, then. That would have been some useful information to have for the hours the candidate put into their submission. Or like "hey, we're going to just skim over this with a subjective list of check boxes".
I have enough experience that I probably would have smelled this before I got that deep into the process and noped out, but for the hopeful mid-level/new-senior devs this sounds pretty demoralizing.
I wonder if your hiring process is skewed by the perfectionists who spend tens of hours of their submissions. Arguably that's the type of thing you guys would want to select for but it's not at all fair for those who timebox themselves to 2 hours or whatever.
What detail is shared about what "checkboxes" the candidate met and didn't meet? From the parent post and your reply, it doesn't sound like much at all?
I've had a few bad experiences when sharing feedback with candidates myself and I would understand doing the checkbox approach for feedback and/or just never sending detailed feedback, but actually grading submissions pass/fail based on a subset of criteria you jealously guard from candidates essentially selects for lucky people. If I wanted to do that, I'd just shuffle the submissions by number of bytes and discard everything that's a multiple of 5 or something.
Did you try paying candidates for the home assessment? People's time costs money. Paying people not only helps attract candidates but also helps the company reduce the list of candidates to take the assessment.
I'm inclined to say the interview process is imbalanced with more power in the hands of the employer. If you're looking for the right balance, try turning over some power from the employer to the candidate.
The candidate's cost was 2-hours worth of time. Was the employer's cost 2-hours worth of time?