Take home assessments can be a valuable part of an interview process but they absolutely need a time limit. I think 2-3 hours is going to give you all the information you need, unless what you're selecting for is new grads with no dependents, hobbies, or responsibilities.
If this had been limited to 3 hours then the worst case is that the candidate would have lost 3 hours, but far more likely is that they would have come up with an entirely different proposal and/or solution that was appropriate for that timeline, and that extra information would have made it clearer what the company was looking for.
The other point I'd always encourage applicants to confirm is: are you looking for any answer, or are you looking for a good answer. Some take-home tests are purely about passing a test suite and how you manage it doesn't matter, some would prefer that you meet 80% of the requirements but write better code. I've seen applicants do the wrong thing on both sides of this.
If this had been limited to 3 hours then the worst case is that the candidate would have lost 3 hours, but far more likely is that they would have come up with an entirely different proposal and/or solution that was appropriate for that timeline, and that extra information would have made it clearer what the company was looking for.
The other point I'd always encourage applicants to confirm is: are you looking for any answer, or are you looking for a good answer. Some take-home tests are purely about passing a test suite and how you manage it doesn't matter, some would prefer that you meet 80% of the requirements but write better code. I've seen applicants do the wrong thing on both sides of this.