To make things even more complicated, besides their imperial title, Holy Roman emperors typically had a whole bunch of titles over different lands within the Empire (and sometimes even outside of it), whose significance in terms of actual control ranged from purely theoretical to very real. Their ability to assert their imperial authority across the Empire heavily depended, among other things, on the ability to draw resources from the specific lands they controlled more tightly.
To make things even more complicated, besides their imperial title, Holy Roman emperors typically had a whole bunch of titles over different lands within the Empire (and sometimes even outside of it), whose significance in terms of actual control ranged from purely theoretical to very real. Their ability to assert their imperial authority across the Empire heavily depended, among other things, on the ability to draw resources from the specific lands they controlled more tightly.