Actually, now I come to think of it
It's at least five. Imagine that.
( Two Hats 🎩🎩, Wed 12 Mar 2025, 10:10, archived)

Makes sense.
When the two you carry about with you require a bit of a clean up, you then have two more to immediately swap to, plus a spare in case some CRETIN does something untoward.
( Dave Trouser ; the people's choice - 75% agree, Wed 12 Mar 2025, 10:19, archived)