I only do takehome assignments if they can be useful boilerplate/starter projects for me and then spend all my hours on them. Recently I had 5 working days to create a backend for a chatbot. I spent about 80 to 100 (including the weekend).

It's good starter code for AI-enabled projects that are cloud agnostic and have good security practices :)

It also, probably, got me the job. At this point, that's honestly secondary. I can create new tools way faster!

One failed takehome assignment, years ago, became an amazing portfolio piece for 2 jobs down the line. The reason the original company failed me: not a standard full-stack web app. I broke the client-server model and made a P2P web app (drawing together etc.).