I have a friend that runs a big band that has been together for years. Their book is in the low two hundreds. All numbered. He'll call out the tune by number. Everybody flips to that page and away they go. I suspect they could almost do them from memory.
My small band has currently 33 songs in the book. The other horn player wants to number them. When I call the song, he wants to know the number. All well and good except I keep adding songs, so the numbers change. Poor guy ends up flipping around. Piano player looks around (all memorized) and asks if we're ready. Waiting on the other horn player is always the reply.
Why so few songs? My fault. All of our songs are originally just for piano. It takes me a bit of time to re-work them for our instrumentation and get the kinks out. We've been doing this for 6-7 months.