When a company produces a new pen kit, unless they want the bushes to tie in with another kit in their own catalogue, compatibility with kits from other manufacturers I assure you is usually the last thing on their mind. I have even seen a discussion on this forum from someone arguing that all kits should be designed to standard sizes so that all bushes are the same!
Bushes though, although ultimately they do wear out, will last for a good long time, and I'm afraid that unless you turn between centres, acquiring a set with a kit that is new to you is part of the game. Making kits to standard sizes is a ridiculous concept that does nothing more than limit creativity, and the safest thing to assume when you experiment with a new kit is that the bushes are unique. But the good news is that as your experience grows, you will be able to sort out for yourself which kits and manufacturers are worth buying and which are not, and your understanding of compatibility will grow with it.
Welcome to the forum Paul - enjoy the journey