What's the protocol these days?
When I started riding in the 70's, there were not many bikes out there, and they were less mechanically reliable, so you'd wave at every bike and stop for any stranded riders.
Now there's so many idiots in cars on the road that I'm too busy focussing on my riding to bother looking at/waving to most other bikes, & half the time they don't return the wave anyway, so I feel like an idiot!
Same with bikes pulled over. There's so many more bikes out there, and I assume that a stranded rider has a cell phone these days.
If I pull over, it's not because the bike broke down, it's because I'm adjusting something or making a call. And most bikes just whiz right by. I'd wave if I needed help.
If you look like you are definitely in distress, or pushing your bike somewhere, of course I'll stop to offer help.