My biggest boa, when I would give her a large rabbit (large for her) she could easily go 1-1/2 to 2 months on that one feeding. I didn't do that very often as I felt it was a bit too large (i'm overly cautious about too large prey). Boas really don't need to eat that often. I usually am feeding my adults every 4-6 weeks but they can (and have) gone longer before and been just fine. As long as you watch your animals and ensure they maintain good healthy body weight, it's fine. Boa starts getting too little food, it's usually noticeable near the tail first. If I see one of mine getting a little thin in that area I know I need to increase the feeding spacing. My adult females that will be bred get pumped up a bit before hand as when breeding they can go 1-2 months without feeding just fine (I usually don't separate breeding pairs until the male takes a break from courting).