Of course there's the other way (it's easier to get forgiveness than permission): do more work than expected in less than 40 hours in the office, and see if anyone notices. One of the most productive stretches of my career was spent in this mode.
They "Work from home" on Mondays and/or Fridays and do very easy work, or commit//send stuff that they managed to do beforehand to generate some easy activities.
If you are performing and producing what you should, this shouldn't matter, but here we are anyways...
My friend worries that if they weren't warming the seat for ages, they would be seen as useless because there are weeks where they just seem to get nothing done.
Exit these relationships.