Custom System Instructions & Token count limit choice

NGL if I’m paying for this service I really expect to be able to enter my own System instructions and to be able to set the generated token count limit myself.

The 1500 / 100 message caps are kinda weird to me and like, I get that they can technically net you longer gens / more tokens for your buck, but I’d honestly prefer to just pay for what I use…. if I only needed a 300 token response, I don’t want it to ramble for 2000+ tokens, which it often does because it seems the token counts are set to their max??? not sure if it really is set to their max or not but it almost seems like it is.