I'll preface with the fact that I do not own a BP yet, just want to cover all my bases before I get one.

If I were to order f/t rats from like, rodentspro or something like that, I'd want to buy enough that it would last maybe 6 months or more so I wouldn't have to ship often. My question then is, what if my snake outgrows the size rats I have ordered? Can I just feed 2, or more often?