This heavily biases your interview process to only take candidates with time to complete your homework: unmarried, childless new graduates. If you tried to give me a 3-day interview I would walk away.
Guess which socioeconomic groups it tends to disadvantage most?
As a hiring manager (Director), I've long maintained the entire hiring process in tech is broken, and this movement toward requiring an arduous amount of unpaid personal time on "homework" is tantamount to abuse. Respect is a two-way street in the hiring process, and it starts with me showing them that respect for their time and obligations.
"we'd like you to just whiteboard some pseudo code for this problem that one of our senior engineers solved recently"
"was he stood in front of multiple people, timed and drawing on a whiteboard when he solved it?"
"no, but we're just wanting to see how you'd approach the problem"
"well, I'd probably do what he did which is Google some stuff, read some stuff, have time to process it, then write some code and then probably restart as I figure out the direction I want, probably bounce an idea off a colleague or two to make sure I'm not just in crazy tunnel vision land and then I might have the makings of a solution. Shall I whiteboard that flow diagram for you?"
interview ended abruptly at that point
Probably it helped that we were in a smallish college town w/o a ton of other tech, & this was a while ago when the tech job market wasn't as crazy hot as it is right now.
(Also, I want to emphasize, it was a challenging problem, but it wasn't a lot of code at the end of the day. If you knew what you wanted to do, you could knock it out in a couple of hours. But you had 3 days to mull it over or try different approaches. We were not asking you to build an app or something similar involving a ton of work.)
I'm sympathetic to the fact that it's a big ask, but I really truly feel like it gave me a much better sense of candidates than just an interview & a resume (what we do at the company I work at now).
It was also a fun problem to solve, and people would tend to continue to refine their solutions (to be better and faster) competitively even after they'd joined.
FWIW.