This does seem to be the case.
It's purely conjecture, but it feels like I've been getting less XP as well. Strange.
Keep in mind that your classes get more xp once you hit 90 with the first one.
Would just like to add in my data.
I'm level 84 on my Black Mage. I already have level 90 with my Warrior.
Did leveling roulette today, got Malikah's Well. For reference, at level 84 you need 7,948,000 EXP to level.
The bosses gave 326,980, 572,224, and 735,708 EXP respectively. This is a total of 1,634,912 EXP.
The actual Leveling Roulette gave me 1,475,100 EXP at the end.
So the total EXP I got for doing Leveling Roulette was 3,110,012, which is 39% of the EXP I need.
In contrast, running the level 83 dungeon gave me 573,436, 1,003,529, and 1,269,845 on each boss, for a total of 2,846,810 EXP. That is 35% of the EXP I need.
So as you can see, levelling roulette does slightly better than a regular dungeon appropriate for your level. Personally, I'd rather do the dungeons. I'd rather not risk getting Sastasha or some other boring low-level instance.
This is a common misconception for some reason.
There is not a switch that flips on once you cap one job. The armoury bonus always works for any job that is not your highest. It is always +100% until the job you’re leveling dings last expansion’s cap, and then +50% the rest of the way to the current expansion’s cap. It is only inactive when you are leveling the job that is the highest level or tied for highest level.
Frontline roulette, FATEs & Zadnor seem like the only worthwhile means of levelling alt jobs at the moment.
Between Praet and Castrum? I don't remember the numbers exactly, but enough to be noticeable, i'd say around 10/15% of a level?
Add to that the fact that despite being shorter, Castrum actually requires more engagement from the player than Praet, honestly I think both should give the same xp.
I leave whenever I get Castrum. The EXP it gives is awful and I can't browse the Internet or watch YouTube or TV while doing it. It definitely needs a buff. Maybe not as much XP as Prae since it is shorter, but the fact that you have to pay attention and move around a lot more (Prae literally has you in front of the bosses for everything past the Magitek Armor) makes it muss less desirable for me and many others.