I don't think there should be a custom limit per account because this means user only are allowed to come up with one idea and that's it for each. Plus what if for example an individual doesn't care about making clothes and are only interested in custom pet creation. That means they have a useless clothing "slot" that will never use.

I do agree there needs to be other legendary incentives for rolling gachas so there is at least something to try to go while waiting for the limit to be reset. Having other legendary items could help make people less likely to go for squirreling away potatos.