I’ve done some Klaipeda quests and some other side quests. Grabbed some EXP Cards Lv.4 and 5 and even Lv.6. I held all of them from Lv. 90 to Lv. 163. LOL!!! I was leveling up only grinding/doing that Lv.100 Mission daily.
When I popped up those left cards I reached Lv.167/12-50%. ._.
I can also tell you guys I have the whole Orsha’s map and its side quests to discover, the whole Fedimian and its side quests to discover, it includes Mage Tower, Main Chamber and other main quests. lol
That looks like crazy, but I’d say I was not in a hurry to level up. I just simply leveled up exploring the maps 100% and killing the certain amount of monsters to get some extra EXP Cards. 
Rushing like a horse is not a good idea if you don’t know what you’re doing.
From now, I would say once I finish all Orsha’s quest/side quests/main quests and all Fedimian’s quest/side quests/main quests, I’ll certainly reach AT LEAST Lv. 190 popping up all the EXP Cards. Well, I hope to reach Lv. 200. 
What I tell you guys is: Do not rush like crazy. Do not pop up all your EXP Cards without certifying you’re doing the right thing. We all know some classes have problems to grind/kill monsters quickly and it sucks, so try to find a party to be helped. Once you reach Lv.50, do the Lv.50 Dungeon as much as you can. At least till you reach 65 or even 70.
Leaving the Dungeon, save all the EXP Cards you’ll get. At Lv.80 grind Royal Mausoleum till Lv.90 because it is great EXP, mainly at 5F where you can kill Mauros and get AT LEAST 20% per monster once you’re 86+. Do the Lv. 90 dungeon as much as you can, once you get Lv. 100 do the Lv. 100 Mission/Daily quests.
Dude, save all your EXP Cards, don’t rush!! Lv. 100 Mission provides you A LOT of EXP. and whenever you reach a dungeon level, get inside and stay for a while. To end this up, explore 100% of the map and at least kill the amount of monsters it requires to get some extra EXP Cards.
See ya