I like to be single brand and model oriented in three major ways:
First, top of the bag until irons
Second, irons
Third, wedges
Putters are interchangeable among numerous brands and styles in the rack of 20.
So, that occasionally gets me to four. I can, however, sport as few as two. I'm as fickle as my game is capricious. Having a blast mixing and matching and still being able to play off a 10.