"I would think that anyone operating from LPL would go elsewhere for 'circuits & bumps' if it was busy"
Indeed, but that adds a lot to the costs, not forgetting the frequent 'holds at the hold' and 'holds at the VRPs' going out from and back into Big Airport.
Somewhere like Barton, you taxy out and you fly which, for ab initio is just what you want. later, you can go into MAN or LPL once you can fly, to polish those RT skills.
Do I detect that some ab intios on here just want to play at being airline pilots while they learn the basics of stick & rudder? fair enough, but that comes at a cost!
You have to decide if you want to pay it.