Originally Posted by
Nikkaszal
Not really, you do it any time at all during levelling when you feel like you're in no danger. Any level, at any point.
Single mobs laughably easy? Pull a second one and cleave them. Still a pushover? Add two more. You see how much you can comfortably take on at once, and then you increase it. Not only does it mean your killing speed increases dramatically, but it also gives you that little extra kick of "I may not actually survive this, better pull off some tricks and play on the edge rather than just repeating exactly the same move sequence fifty times in a row".
Do this in any game where you feel safe and unkillable in solo content. Keeps you from getting dulled. If you find yourself still plowing through eight mobs at once, great. Next time, pull twelve.