I returned to the game about a month ago after quitting around when PVP stopped getting updates. I'm having a lot of fun, but I'm really curious about the pace of progression as I get into the latter stages of the game.
I think I'm in the mid-game. I have Starforged Gauntlets (no idea where they came from), Swain's Raven Army (bought), Perfect Hex Core (bought), and Harmless Scarecrow (Glory). Between Aurelion Sol, Swain, Viktor, Viego, and SB Teemo, it seems like I should be able to clear all of the available adventures in time, and the Weekly Nightmares are no problem. So I'm having fun.
But I can also see that Monthly Challenges give really good rewards. I know I need to keep at least 600 Glory on hand in case I see Searing Brilliance or relics for champions I like, but in addition to that it looks like Platinum Chests and region-specific star chests are valuable.
But man I absolutely loathe Monthly Challenges. There is nothing more infuriating than spending 5 minutes on a decent duel then another 2 minutes in fucking loading screens. Do I have to? Can I reasonably progress to getting a few 5-6* champions, get Epic epics, beat Zoe with a few champions, etc, without grinding these things out?
Edit: Thanks everyone, sounds like the consensus is that Monthlies are skippable as long as you're doing the Weeklies, but that they do provide good rewards. Happy with that, I might just leave them alone most of the time and dip in when I feel like it or need to buy two Relics in a row.