In contrast, when I worked in office, I found these fabled “lunches with the guy in accounts or the women in the sales team” didn’t ever happen. A lot of the mythical spontaneous collaboration that supposedly happens in office seems to be just that: a myth. At least for many.

They happen all the time for me at small to medium companies. If the legal team is two people whose desks are by the door, then you are going to eat lunch together at some point. It would be weird not to! Just wait until someone says "anyone want a coffee?" or "who brought lunch?" and then stand up.

Obviously this doesn't happen when the legal team is located three buildings away. At that point you might as well be remote from the perspective of collaboration.

I think only a few people manage to build such a network inside a company. But those are usually the successful ones, because they know much more than others.

If we're collecting anecdotes, it happened for me in more of my office jobs than not. Might have been relevant that these were smaller offices.