The games at Chimera in August are all about 3 hours long. There are 6 timeslots over the weekend (each timeslot has several games to choose from), so you can play up to 6 games over the weekend. So the lengths are about the same, but there's a big variety of styles in the games from intrigue to adventures with live combat & foam weapons, across a lot of genres. Great way to get a taste for a variety of larps.
A lot of evening games are on Saturdays, to give people Sunday to recover I guess. Unless you work Sat evening that should be okay though? Full-day games happen on Saturdays and Sundays... possibly more often on Saturdays though. Game organisers just schedule times for whenever they think will suit the players, there's no particular structure to it. Although weekend events almost always start on the Friday evening and run through to the afternoon on Sunday, to get the maximum amount of time in while leaving some time for debrief and cleanup after.