Yes, that kind of spur-of-the-moment exercise is probably the best way for me. I try to set aside bits of time during the day for the PT-prescribed exercises but probably wouldn't be willing to set aside any more time segments as "my exercise time."

I used to do that--gave half an hour a day to running an exercise video and following along with it but as time went on I began to wish I had that half hour for other things I preferred to do, and so... now those exercise videos are gathering dust and I just try to make sure I do enough steps each day.

But i could occasionally pause long enough to work in some of these.

I've been doing the side leg raises and lateral squats daily for several years now as part of the routines prescribed by a PT.