Its every 5 days upto 500 Grams. Every 7 upto a kilo Every 10 upto 1.5kg Every fortnight over 1.5kg
Its just a rough guide though. If your snake only eats a few months in the year you're going to want to give it more than a snake that eats like clockwork. You do find the balance though and it does resemble this guide quite closely.