I switched from 5 to 7 days at around 600-800 grams. I noticed my snakes weren't out looking for food or even refused on the 5th day and then took it the next feeding (so on the 10th day). That's when I switched.
I feed smaller meals more frequently rather than larger meals less frequently. I still offer to my adults every 7 days. But nothing larger than a 80-100 gram rat. Even to my biggest girls.