It would be great if you had credit balance under $4.95 and you had like a conversion option to spend it on BC/R$. The amount of days you get (for BC, TBC, OBC) are based on your remaining credit balance, or the amount of R$ (preferably 4¢/3 R$).
Often, when you have like $2-3 in your credit balance, you’d have to buy another ROBLOX card to get rid of that by buying TBC/2 months of BC. People who want to not spend anymore would want to just clear it out on the spot without having to buy more.
Minimum amount of $ you must have is 1$ for BC, as it reduces the risk of abuse (getting 100 groups from OBC and switch to BC). Lower than that can be converted to R$.
I’d rather just be able to tack the balance to my next purchase (say I buy obc monthly for 20 bucks, but I have 3 dollars in credit, it would just reduce 3 bucks from my purchase, making the total 17)