I’ve read lvling guides suggesting to grind in instance dungeons. Does mobs there give more exp as proportionate to their increased toughness? Otherwise, I’m of the impression that it’s not efficient to spend 3 times the skills/effort and getting perhaps just 1.2 of the exp (multipliers here are just random numbers that I used to illustrate my point)
Instance dungeons give great exp. At level 50, my very first run of the lvl 50 instance with a group gave me 6 levels and it took 15 minutes.
2 more runs later, I was lvl 60. So in total 45 minutes for 10 levels.
I kept on running it until 70, which took maybe a total of 9 runs. So Level 50-70 in a total of 3 hours across 3 days if you include the time looking for party.
Yeah, the good/bad thing about instance dungeons is that you can only run it 2 times a day, which is think its fine to avoid spamming, what you can do is to do this 2 runs, and level like 5-7 levels, and then continue doing quests without using the exp cards, when you feel that dungeons does not give enough exp, time for those cards until Reset Level again.
I see. Well then I guess it’s because that I’m lvl 81 and rank4 that the mobs there aren’t giving me any exp anymore (even to my lvl3 class)…
Next reset is at 86 so grind for a couple of levels then card boost to 90 and unlock the next dungeon.
That’s because you are almost reaching exp reset 
at 86 there’s an exp reset, so at 86, do some little grinding (like 30 minutes) and you’ll be level 90, then continue with dungeon lvl 90, in 2 runs you’ll be like 98 or so.
Do quests (i did until i got 276 Exp cards (106 exp 4, 160 exp 5) and went from lvl 101 to 115.
There’s a level penalty so you’re actually receiving lower exp because your level is too high. When you’re within the level range the exp you get from mobs in dungeons is crazy 
Thanks for the clarification guys. I guess I’ll go grind myself up to the exp reset first.
I got from 90->92 first Run and 92->94 the second and im using token+PF.
115er Dungeon was ~1 Level/Run
130er <1 Level because lvl.136 is exp reset and u can kill the endboss realy fast,
if u dont know he is the Endboss^^
145er again ~1 level/Run