Return of Reckoning

Yes, but during your farm consider using xp reduction scrolls, they do at least work for pve so you wont outlevel your renown rank too much (catching it out alone and pugging is pretty bad experience hence everyone advice to grind at least 40+ (closer to 60 is ideal, but for that you need succesful (lots of kills, lots of winning zone/forts etc) orvr sessions and no side activity) renown when you hit combat rank 40).
Also if you struggle to find more people (timezone or odd playtime) to do PQs for mayhem then you can consider grinding some others PQs but lower level that you can quickly solo and just take crests to buy gear.