A lot depends on how the actual work is tied to the daily cycle. A retail store wants retail hours attanded, even if 12 hour days = shifts. A insurance office could probably run 4 days of 10 hours each = same work, as most document work is not tied. Workers might like 4 10 hours days = 40 hours. worker will not like 4 days at 20% less, and office will not want 4 days at 25% more.
Logic says 4 days of 10m hours each meets wage, work and free time expectations.
no one want less pay, not employers more wages.