My personal experience is, of course, not representative of an entire industry, but I just have a hard time imagining it being a common thing. I like working with other people and helping juniors sort out their problems, but I'd quit my job if I had to take turns writing code while someone else watched and just sitting and watching someone else writing code. Both of those things seem horrible, to me.
'course we only did it for like 5 min to get him over the hump.
I think that's the only use case. It sucks having someone hover over you otherwise.