Short: Too late to save the leveling pace in this Umbral Era. Let the Seventh Umbral crisis adjust leveling for 2.0+. Haha! Dodged that phone call, I'm on a computer (Sanguine Rite for posting)! It's fast until 10, slow until 30, then faster than expected after 30.
Extended and skipworthy:
Anyhew, I feel that levelng is a strange beast in this game.
If a player uses leves and behests at early levels, they will level at a slow pace. Duoing (alt lancer and gladiator), we deviated to some marmots in Black Shroud, jumped up from level 3 to 9 in about a good 30~40 minutes and sold their pelts for more money than we were getting from leves.
Things slowed down again and the combat difficulty for other enemies was enough that the downtime was longer with starter equipment and a slightly updated weapon.
Levels 10~29, the combat, gear, and leveling options are far less.
To do better in combat, you usually have to cross class at this point (Second Wind, Cure, etc.)
Leves generally don't seem worth the time for XP.
Weapons take more time to acquire (make them yourself, NPC ones spaced out, market costs good chunk of gil).
Armor is easily worth it, but similar to weapons and are usually a good 6+ levels spaced out before you find a successor.
As your combo options increase, your damage mitigation and healing abilities expand, entering an arena where more gear is floating around, combat goes quicker post 29. And leves start becoming worth their time in EXP (both company and non-company, except Nanawa).
Where in many other games, I would expect leveling to be slower at higher levels, it picks up. In this, it seems like there's enemies yield more XP, less downtime, killing faster, more gear options, more locations.
... OH! Forgot to get groceries, I'll be back. ... maybe