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?
Try having several options for workouts you enjoy. Sometimes I do a single set past failure of bodyweight exercises for a great and efficient workout under 10 minutes. For quick cardio I do sets of sprints to failure in under 20 minutes.