How many systems do you have?

Living room home theater. Bedroom 2 channel. Headphone system at the office. Custom in ear monitor system for mobile/travel. 

Ha! 
main system , bedroom , vintage system in playroom, atmos theater in garage, gym system, work system… 

5. Office, living room with HT system, bedroom, basement/poker room, and outdoor patio. Living room also powers outdoor porch speakers. 

2.

One gets used 95% of the time. The other one doesn’t get much use, about 5% of the time.

To me, 1 system is more than sufficient, spend all your money to optimize this single main system. The most I would do is 2 systems although the 2nd one won’t get much use. It’s a waste of resources to have multiple systems where they don’t get much use, systems which are built mostly for display instead of listening particularly those which are built around high priced equipment and speakers. If the whole system costs less than $500 then that’s another story.

Four. Home, vacation, two offices. Three vintage. Two with vinyl. One Class D. Zero Tubes.