I would definitely stop the 10% t0 15%. That a great rule to follow while they are growing but once the snake is an adult you can go to 10 or more days between feedings and got down to 5% to 10%. There is no set rule. Is this snake male or female? Are you breeding? Does the snake refuse meals often? You are going to want to feed a breeding male far far less than a breeding female. The male needs to be kept lean and the female needs larger feedings to support eggs but not so fat as to reduce fertility. My advice to you would be get a good scale. Weigh your snake often and then graph it out. If the graph shows a trend toward losing weight then you are underfeeding. Otherwise you are doing just fine.