A consulting firm called PeopleSoft(? I think that was their name, someone will correct me if not) did a fantastic study of developer productivity in the late 80's or early 90's. They found that developer productivity was most strongly correlated not with education, years on the job, title, salary, or any of the obvious stuff but with:

1) Square feet of desk space

2) Ability to divert incoming phone calls to voice mail

Square feet of desk space might sound absurd and pompous, but it was a real advantage. Large monitors and powerful IDE's and code search tools were still decades in the future. As a programmer you used a printer and you kept stacks and stacks of printed code on your desk. The more square feet of desk you had, the more efficiently you could lay out and sort through the printed code you needed to look at (this is why Elon told Twitter engineers to print their code - he's a boomer programmer who grew up in this era when that really was how you read and reviewed code).

Phone calls to voice mail is more obvious today, but that study was I think the first to point out that programming was a flow state activity where it typically took about 10 minutes to get your mind loaded with all the info and context required for peak programming productivity. They observed that one two minute phone call was enough to wipe all the context out of your mental stack and drop you from peak productivity back to minimal productivity. If you had one small interruption every ten minutes you never hit your peak flow state as a developer. (With the massive improvement in IDE's and etc, I'm curious if that preload timescale remains consistent or has dropped but I'm not aware of anyone doing more recent work on that question).