I keep my horses' tails braided year-round. I love long thick tails so that's how i get them. During the winter they're wrapped in vet wrap and during the spring/summer I have a bailing twine loop with more tied to it that i add when i loop the braid back up for a fly swatter :) I use leave in conditioner for people and take it out when it's starting to look ratty rather then every week.
And in my opinion it does work,for the most part. 2 years ago I had a horse swish his tail ACROSS my clippers while body shaving him and it shaved off HALF his tail all the way to his dock, I braided what was there and 6 months later you couldn't even tell! and I only had to trim off a little over an inch from the other side to make it even.
On the other side I have a gelding that it's taken 3 years to get his tail to grow from his mid cannons to the ground. but now that it's there I ain't ever putting it down ;P