There's road bands. These are quite often not recording bands.
And then there's rehearsal bands, which are neither.
And then there's gig bands, which is a world apart from any of that.
Economics are a factor, but not just for a leader. There are plenty of sidepeoples who can make more staying in town than they can from doing road gigs. And travel...
If appearances are to be believed, Sonny kept a fairly stable core/corps of road players and Clifton Anderson kept everything right with them. The wild card, until the end, was the drum chair. And that didn't begin in the 70s!
On records, though, Jack DeJohnette was used more than you might think, and the few records with Tony Williams benefit greatly from his presence.