As for doing it all over again, I tried. However, it’s just too big of a time sink.
I play on my maxed out US server because there’s literally no commitment. I don’t have to keep up with the FWotD bonuses. Even though I still rack up Mutation Bounties, this is only once per week.
Don’t get me wrong, I had fun leveling up, everything, the first time. However, as far as progress on Europe goes, I’m only on lv57 (if you look at my post above, that’s pretty much just 27% of the way through, and that did take a bit of time alone! Can’t imagine repeating that 3 more times).
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If I were to soldier on with Europe region/server, I would go with what’s been suggested… level up more COs, and their prestiges, so you’ll have more variety when doing Mastery. It’d also give Mutation Bounties better utilization since you may not be able to do some Brutations with some of them COs and prestiges at pre-mastery. If you can, then it’s a great way to fast track through that!
Once you have more of them unlocked, along with some of their prestiges, it makes Mastery (not to mention Ascension) more variety, choices, and fun! My path to getting through Mastery, I only had Karax, Swann, and Stukov. Wasn’t that bad, “but still”.
Also, I would totally ignore some prestiges the 2nd time around, and even downright COs, to save significant amounts of time. I don’t really use them because they’re not my play style. Off the top of my head… Swann, Fenix… stop at P2. Don’t bother with Mengsk, at all.
I only forced myself to do so as a fun experiment… my “tour de prestige”. It took me 1.5 years (gained 400 Ascension levels) to try each mission, with each CO, on each of their prestiges, at least once. Regular Brutal, bonus was mandatory.
While we’re on metrics, it took me 8 months to do all 54 prestiges (from P1 to P3, inclusive, of all 18 COs)!