Custom Maps XP Rate

So I've been doing a couple of custom XP maps, and the videos and people's feedback are always saying they get at least a 100k XP before going AFK, then after a few hours of being AFK, they have 250k-400k XP. However, when I try it out, I always end up with around 60k XP before going AFK, then I start getting XP at an extremely lower rate when AFK, so I don't think I would reach 250k XP from a few hours of being AFK. Does anyone know why my XP rates are so low compared to other people's alleged XP rates? Is there any way to fix this, or should I just deal with it?