i actually just saw my leo shed for the first time (although it wasnt its first shed ever) and ive had it for about 3 months, but it only took about 10 minutes and it was completely done... i dont really have anything to relate to since this is my first leo, im not sure if its other sheds have been as quick or not?
We have had leos begin to shed at night and still not be done by the next day. They seem to get tired and sleep it off for awhile. Sometimes they shed it all at once, and sometimes they just don't. I wouldn't worry as long as they don't have any shedding problems on these key areas: toes, eyes, mouth.
You can just leave the skin that's on top of his head there, but if you'd like to pull it off, you can do that too. I recommend giving him a warm water soak before pulling it off though, just to make sure the skin gets loosened nicely.