The reason is kinda simple:
The monsters at Alvida are 25-30. So you enter at 20 get high exp due to the Lv 25 monsters. When you're Lv 28 and the monsters are 30, you still gain such an great amount of exp since the x25EXP potion, the regular boss exp and you also gained some repeat bonus on your way to that.
So I just try to find a dungeon where I can do several runs without the need to get to another location to gain as much as possible from the repeat bonus. My route would look kinda like this:
20-30 Alvia (Steven Trading Port)
30-40 Atoo (Dangerous Caverns)
40-50 Paul Burnaun (Pine Cone Hills)
50-60 Arka (Frigid Canyon) -> may use something else there, since Arka is kinda annoying
60-70 Kryos (Verglas Ridge)
This is copied from Xydor on another Thread
I did the maps which where in the same lvl range as me or a bit higher and spammed F1 with 3 maps there, the repeat bonus will get higher and higher and u will earn more and more exp, it took me about 1-2 hours to get from 50 to 60 :p
