I maxed this out on a solo character, it was rough. I think I did it in 2 or 3 seasons of a TV show, so it wasn't too bad. Wouldn't multibox it though unless there's some feature in the future that allows sharing of the dig sites like quest drops from mob where everyone's guaranteed to get one.

My overly generic advice is if there's a reward you want, go farm those dig sites to level up. Even if you have to go clear other dig sites for artifacts you don't care about just push site respawns.