I work in a small company and so extra hours are every day common, however I was able to shoehorn 2-3 Hr a day for ATPLs, I already have PPL. I managed to get a 1.5 month leave to finish the exams and hour building, when I come back I will work on a 4 day/week basis leaving 3 days for training.
I think it really depends on the company needs, we are working shifts so there is always a mean to sort things out.
I got the feeling from other posts that IR would preferably not be done part time as it can be tough