This is the first season I've actually bought the battle pass up front and really focusing on leveling via challenges. Is it worth the effort to try and finish off all weekly challenges, or is it smarter to wait for later weeks because there will be overlap? For example, I have a deal 2500 damage with shotguns challenge (kinda painful w/o double tap trigger this season), should I grind to finish it off or wait for a "deal X damage with Mastiff or Eva-8" in later weeks?
I don't really grind weekly challenges. Generally everything starts coming together towards the end of the season. You'll deal that much shotgun damage over the course of the season easily.
If I get a 'kill 15 players with 3 character I rarely play. Then I'd probably grind that one out in casual.