Putting a limit on badges per day works in a scenario where everyone is at this event for the PPL and that alone. People have to budget their time over the course of the weekend, this includes both leaders and challengers. Should someone be restricted because they were fortunate enough to find a few gym leaders early on? If you are able to "hop from line to line" and face a bunch of leaders, that's saying that A) you have the time to, B) the gym leaders have time to sit there for however long that takes, and C) the lines are moving somewhat swiftly. At the Friday meet-up, I was one of the first ones there and was there for an hour and a half and battled 2 leaders. I hopped from line to line. You can only do that as fast as the lines go. I do think that sign-in sheets should be done away with. I know people were hopping from sheet to sheet and, in effect, in multiple lines at once. That, I can see as being unfair.
I don't know what the best solution is. I just don't think that restricting how many leaders a person can challenge in a day is the right way to go.