They definitely do in engineering - USC and UCLA had most of its PhD students working full time in industry and only part time in their PhD program and grad school generally. I know because I was one of them.
I did a part-time PhD (not in the US, so I am only responding to the latter part of your comment). It's hard, exhausting and can occasionally be frustrating. I gave up most of my weekends during the time. My sleep hours were less than what they should have been - and I did this for years. If you're wondering, it did lead to some health problems (esp. my back), thankfully not major, most of which I've recovered from.
Do it only if research really interests you - this was my case, so the sense of gratification from learning and finding out things offset many of the negatives. Also, having a patient advisor and good friends helped a lot.
Out of curiosity, since you've gone through this before, do you have any advice on the best way to manage your time doing a part-time PhD.
I've started my part-time a month ago, and it's been pretty exhausting already, and I suspect it will get harder. How did you budget time to talk to family, or to do something for yourself to avoid burnout?
It was hard for me to set aside specific hours of the day for PhD during the week - because I occasionally had early morning and late evening meetings for my day job. And on some days the work itself would spill over. So the simple policy I followed as: if I am not involved in work from my job, work on the PhD. Far from simple to follow though.
I'd often work out of cafes and libraries (I used to cycle between a small set of my favorites), because the change of atmosphere, and often the ambient activity, helps. Not to mention, if you're tired and trying to work from home, it's easier to get distracted (I could justify dozing off), than when you're at a cafe with your laptop in front of you and there's little else to do. I found that university cafes can be particularly helpful because you see a lot of people working around you.
Family and friends: I didn't really plan talk time with my parents or friends but was mindful we talk without too much of a gap in between (at least twice a week with parents). I used to reserve the times when I really needed to unwind for these chats. Note: I was single for most of my PhD, and got married when things were winding down.
On weekends, I would typically allow myself Sat morning off for a change of pace. On most weekends, I would drive off out of my normal ambit of travel, and work from a cafe/library away from home.
Of course, none of above advice worked during the pandemic- working on the PhD became relatively harder then.
Essentially, since I couldn't have changed the amount of work I needed to do, I substituted that lack of variation by constantly changing the atmosphere I worked in. That helped a lot.
Fair enough; when I reached out to schools within commuting distance of me (the general NYC area), none of them offered any kind of part time plan for Mathematics or Computer Science (the only fields I'm really interested in).
Sadly, there are not a ton of universities that offer an online PhD in CS or Math, meaning that I was limited to what I could easily get to via train, at least in regards to schools in the United States. Eventually I found one school in England that was willing to let me do a part time PhD online, which is where I'm enrolled now.
Yeah, a friend of mine has a PhD in Economics, that he got while working full-time at FDIC. I know a number of people working full-time at government research labs in various math and science fields that are PhD candidates. The part-time PhD seems like it's extremely common as long as there is real, employment-market demand for that PhD, too.
On the other hand, all the history PhDs I know can't even get work at their own university.
