Ah, I see, by "songbook' he meant the equivalent of Yamaha's Music Finder Database MFD, and not MIDI songs. I have used the MFD some, but in most cases I've elected to create my own Registrations instead, if only to customize things a bit more to my liking. With my iPad and unrealBook app and the MIDI data that I'd set up to recall Registrations for me, I can get a song's Registration loaded and ready in ~1 second, so it's still fast enough fro my needs.

But as some have said, the MFD (or "songbook") is sometimes a good place to look for ideas on Style that suit a song you're going to do, a possible Tempo value, etc. Somewhere in the past, there was an Excel spreadsheet with all the "stock" Yamaha MFD data in it. (Yamaha's MFD from some Tyros, with corrected song titles etc.)

Jim