A question has been bugging me all they, so I figured I will share it with the community.
After the first three dungeons that are basically there as a tutorial, new dungeons come up at a predictable interval of 3-4 levels ending with a 3 level gap between Aurum Vale and Castrum Meridianum.
Now in Heavensward we will have 8 new dungeons. It is reasonable to assume that the ammount of xp gain for a dungeon done at the minuimum level will be rougly the same as now. Meaning, you will probably need to do the same ammount of dungeons for a level you do now.
But how often will we get a new dungeon? Doing a dungeons at every 3 levels is not possible as we only get 10 more levels.
One way to do it is to give one dungeon every two levels, starting at level 52 and end the storyline with a series of 3 dungeons (much like in 2.0 but with a 3 dungeons instaead of 1 trial and 2 dungeons), but I am not convinced that the MSQ will have us run around doing fetch quests for two level before giving us our first new dungeon.
Of course there can be any number of trials we don't know about (at least two). But there were levels when we got dungeons AND trials. (Ifrit and Halatali, Garuda and Dzemael Darkhold).