Some cats figure it out and some never do it seems. Cats have very sharp claws and can easily grip trees to climb up, but since the nails curve backwards so much, they do not offer any grip at all for going down headfirst. It is when they walk out on a horizontal branch that they are most likely to have trouble figuring out how to get in position to shimmy back down. Our MC mix was excellent at doing the shimmy down, but I have seen other cats get 10' up and then just let go and push off to get back down. Worst descent we ever saw was a cat that our MC mix had treed, who had gone more than 20' up. We took our cat in and waited and waited to see how this cat would get down from such a height. It came down headfirst, jumping from branch to branch, but eventually missed a jump and came crashing down the last 10-15' through several branches. Luckily did not appear to be injured.