The worst thing to do in a map are the checkpoints: after you have made some very cool parkour puzzle, you have to find spots where to put checkpoints and to be sure that are working and that the command blocks are not visible.
If you instead are playing a parkour map, surely you feel you need more checkpoints and you're yelling every time you fail a jump and you have to start over or to simply wait until you're dead in the void.

But with very few command blocks, you can easily create a checkpoints system incredibly simple to set, making happier you, because you can now only concentrate on the parkour, and the players, because he now have more checkpoints during the map!

How? Check out this video!