We should get exp boost in the game.

[Dfess]

The player who managed to do 1-50 in 3h 56m 25s /played in the Shadowlands Alpha, also speedleveled a warrior from 20-120 with the Winds of Wisdom (100% bonus exp) buff. Total duration was 12h 29m 23s. This is with full preperation for speed leveling, including heirlooms, enchants, XP potions, and any other items that could help him while leveling (war drums, mount speed increase items etc.).

It'd be a bit faster as a monk, but keep in mind that the +50% monk exp buff changes to a +mastery buff upon reaching lvl 90. It also goes down to +20% upon reaching lvl 85, but only once you relog after reaching that level.

Even still, You can't reach 80 in ffxiv in 12 hours. It takes days compared to one day in wow.