So, first thing look at the screen:
From level 1 to lvl 105 you have to get 349.716.643 exp
Hardest grind dungeon on JP version gives 1.296.002 exp per run which takes 20 minutes to finish
JP exp rate = 1.0
US exp rate = 0.2
1.296.002*0.2=259.200exp
On our version we would have to do one the same dungeon 5 times to get equal amount of exp to JP.
5*20minutes=1h40minutes
Consider that for most 35lvl+ dungeons you will have to spend at least 20 minutes to finish them and they doesn't give you as much exp as JP one and it makes the grind even longer.
I just thought that it would be good idea to show how does look grind on higher tier level because people qqing already about higher exp rates at since level1 that 1/10 or 2/10 is too much, we should have 0.1/10