The median time for takehome assessments in the industry is 3 hours, with the longest taking 10 days. Only around 10% of companies compensate candidates for their work. https://www.careerfair.io/takehome-assessments
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For my jobs, I typically have to do about three tests--usually a couple of assessments that take about an hour total, and a writing/editing test. That test can take anywhere from an hour to four hours... and there's never been any consideration of getting paid for that time.
I have declined to do writing tests that would take longer than a couple of hours. If that's their expectation during the hiring process, it's not a good indication for the company.