>>12713423Pretty obvious the secret to making the big yen as a freelancer is being a merch mover. Just getting booked numerous places wouldn't be enough. Those three you mentioned are all big merch movers and always have long lines at the shows they're on.
Yukihi also said her NOAH and AJPW appearances added to her own fanbase at other promotions, another benefit of freelancing you're not stuck with the same crowd over and over.