How many systems do you have?

Three.  Main in living room.  Secondary in dining room/den (sounds as good but slightly different than main.)  Tertiary in bedroom.  All handle CD/SACD, first two phono as well.  All have tuners.  First system has RtR Dolbyized tape; bedroom has Nakamich cassette.  No streaming (at least not yet; perhaps not forever.)

4

Den

Bose cd player in the garage only when washing the car

Car 1-Bose factory option

Car 2 -not sure

Had 3, but down to 2; I sold off my headphone system due to lack of use.

Four.

Main one in the living room, smaller one in the dining room, former main components in the bedroom and one in my office. All that in a townhouse of less than 1,000 sq ft :-)

Two is a bare minimum.  One is the main system, the other is made up of hand-me-downs from the main system, so you get more mileage out of replaced components before they leave the premises.