I pulled that number out of my ass.
I don't even know where I came up with it. Really.
The other day, I determined that I was absolutely going to time one of my rides. I looked at my phone. Got on. Rode. Got off. Put horse away. Cleaned tack. Went home.
Sooooo. No clue. It seems like important information as far as measuring fitness levels, so I'm going to redouble my efforts (if I remember) at some point in the near future. In the mean time, does anyone else have any idea how long they spend in the saddle on an average day?