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?
You do what you can, when you can.
Like, I’m disabled now, so the days of three hour long dedicated workout sessions are long gone. I can barely manage anything that takes longer than cooking a decent meal, and the more impact there is, the shorter the time gets. So, you know, serious cardio is out.
However, you can exercise anywhere, any time, assuming the situation makes it feasible at all (might have issues at work, etc).
So, you cram things in. Sitting at a desk for fifteen? Keep your legs moving. Reading files, you can do so while finding some kind of activity that fits how you’re reading. Laptop on your knees, maybe you do some curls. Have a tablet you can use, or paper files, do some pushups while you read.
If you’re going to have only one single session, make it cardio. Nothing else gives the same time/benefit ratio, and you can do different cardio depending on where you are. So, you might only have an hour, use it running since you don’t need a specific gym or piece of gear.
Gotta work with what you’ve got