I can safely say you did it wrong, but we all did on our 1st characters. I completely skipped the mausoleum chapel on my 1st playthrough and that area is like grinding candy. Mobs die very quickly and you can go there as early as level 65.
I plan to grind there from 65 to at least 75 maybe even 80, then continue with the quests. Grinding in the lower area’s of the mausoleum is less exp.hour since the mobs take so much longer to kill.
I was able to break down the 86 wall with exp cards.