115-116 you make an average of 1.5-2% per day at 1000% XP bonus, when killing 80-90b XP/mob in high area and 400b XP/mob in Swamps of Screams twice a day.
So one needs approximately 60 days = 2 months to level from 115-116 which is pretty decent without Dethrone.
Speaking about someone who runs +30 Limited Weapon and fairy reasonable gear.
120-121, you are happy if you make 0.5% a day!
Don't expect to XP in the same zone after next big update, free to play has always to go back 1-2 zones.
If you don't do at least 2% per day at your current level for everyone <116, don't expect to hit 120 in the next 2-3 years, when everybody will be 125-130.
And Aden dailies + Castilla + IT + Hunting zones are maybe 10% of the game, rest 90% you are doing what? Afk and play Playstation or Xbox.
The game is siege, daily sword fights, pvp in open field (bother actually people), Dethrone fights, Ceremony of Chaos, Olympiad, trades/buy/market analysis, free events, farming books, trade gear to alt toons to farm more in order to progress in a reasonable way, unless Visa/Mastercard allows you to skip those.
If in 2-3 years, you are unable to stay alive for more than 10-20 seconds in Giran, Rune, Schuttgart or Aden siege, you will never do them and you will hit mobs forever.
Last update we got, they wanted people to be 115 for the skill requirements. Collection wants you to have main + dual 120. They implemented skills until 120. This should give pretty much a sneakpeak what happens next, 121-125 is the new goal.
Everything below is playing catch up and is difficult without spending a reasonable amount of money, or playing smart the market.