Some people get everything done first thing in the morning and are useless in the afternoons.
Some people can't get started until noon whatever their local time is.
Some people can commit to 10 or 12 hour days, and if so, it's not fair to ask them to work 5 days a week at that rate.
Some people work best in private offices, some at separated workstations, some at big collaborative tables, and some at home. Some do best standing, some walking, and some lying down -- all different from the ones who do best in a nice supportive chair or on a stool with no backrest. Some need an ergonomic keyboard, some need macros, some need a giant screen or 2 screens, or six. Some need screenreader software and some need speech-to-text.
The relevant questions:
* are they productive in some arrangement? I have seen a very very few people who seem to be always rearranging things and changing equipment and hours in a constant pursuit of distraction. The vast majority of people figure things out and settle into a steady state of productivity...
* is the nature of the work conducive to the desired arrangement? If the position requires customer or vendor contact or operations response, the coverage needs to be maintained (and handoffs need to occur smoothly).
* is the company culture amenable to alteration or accomodation? At one workplace, most of the people I worked with didn't come in until 11am and liked to schedule meetings at 6pm. I liked to leave around 5:30, having been there since 8 or so.