in vertical caving i've often prussicked back up the double line used to rappel in.I have used this method in teaching people to get up in a tree. I use a prussic to my saddle, then I use a line attached to both feet , in the middle of the line i attach a carabiner and hook that to the 2nd prussic, thus equalizing the feet each time you stand up. This allows for easy ascending with minimal excertion and only tending 2 knots. I like this method because the gain each time you stand is a full arms length. The down side is having to teach changeovers and how to go to drt when in canopy. Its been a good method to get people up with energy to spare in the tree. I like teaching the blakes hitch to, but it takes people a little getting used to before making the bridge longer for bigger gains on the ascent.
Just something to play with.
climb safe