are there days where you only train certain parts of your body / only do certain exercises because you simply don’t have the time for a full workout?
my ideal workout means stair climbing, running-walking and stretching. It can well last 2 hours.
Some days I don’t have enough time to do all that. Would it be better to do less of each kind of exercising or just to fixate on one kind?
This is a shorter answer than I typically would write, but any sort of exercise program should be atuned to your specific circumstances, since if it’s not practical to execute upon it, then it’s not going to sustainably achieve its objectives.
As for me personally, I wrote my program based on a friend’s five-day-per-week program, which splits the days into: arm day, back/shoulders day, chest day, leg day, and core day. I specifically do not want to be overworking certain muscle groups without adequate rest. Each day takes no more than 60-70 minutes, including warm ups.
Might I suggest posing in c/gym or c/homegym for advice on how to tune your current program; there shouldn’t be a need for a full rip-and-replace.