In the case of engineers and programmers, the amount of useful completed "work" has only a very weak correlation with the length of the workdays.

Good engineers or programmers will think anyway most of the time about the problems that they must currently solve, regardless whether they are in the office or at home or in any other place, and regardless whether to an external observer they appear to be "working" or they appear to do nothing.

Programmers who spend all day typing lines of code into a computer, are more likely to not be competent programmers, because otherwise they would have found ways to automate such activities that require continuous physical involvement, making impossible the allocation of enough time for thinking about the right solution.

If whatever they do does not require true thinking, then that is the kind of job that can be done by AI agents.