Of course there are differences, but no one's over training from 4 sessions a week.
I haven't met anyone who trains hard and consistently 3-5 days a week that hasn't made progress. Everyone I've met who isn't making progress is simply not putting in the effort or having the consistency to do so.
I've never met anyone in real life who I could put down over training to their lack of progress.
There are some guys who train 7 days a week who aren't making progress but they're pretty big and strong and are probably at their limits. Maybe if they trained less it might help but I doubt that's what's limiting them.