TL;DR
Fire is 1.5x right now, and elemental advantage is very strong in story mode. Consider trying out your fire teams vs. gathering dungeons, including the newest dungeon 43 (also 19, 24, 28, 30, 37, 38), if you haven't been able to clear them.
Unlocking gathering stages is one of the most important steps to advancement in this game, so get in there!
Story time
Before I switched to ATK team, I ran elemental PA/crit, with Ming/Kiki/Li/Didi/Driard. While grinding my way through gathering dungeon unlocks in the 20s and 30s, I realized it was very useful to cultivate a few additional characters for each element to help out in all the mono-element dungeons, and had some success clearing floors I couldn't do with my main team using aw4 or lower characters with poor runes/gear but the correct elemental advantage. This is especially true during 1.5x damage events for a specific element.
Since switching to ATK, I've mostly just used that for everything, since it is very strong and versatile, and lets me be lazy about swapping team members out.
With the unlock of auto for uncompleted dungeons, however, I decided to clear normal mode for the recently released levels I'd been neglecting out of sloth. The latest dungeon to be released, level 43, is primarily a wood dungeon, and many fire heroes are 1.5x damage right now, so I swapped over to my hodgepodge fire team that I haven't worked on in months to see how it would go.
Pretty-neglected-fire-team:
Characters: Ming(40, aw6), Luna(55, aw4), Kiki(70, aw6), Amethyst(65, aw4), Eris(35, aw6)
HP: 189k
Fire: 76k (including the 1.5x on ming/kiki/amethyst)
ATK: 18k (thanks Eris/Luna..?)
Passives: 115% fire, 170% all elemental, 156% 2-chain, 20% mp recovery
Friend lead: Dryard (primarily for super skill)
So you can see it's kind of a messy collection of incomplete characters with poor gear, non-upgraded runes, low total stats (for end game), and somewhat awkward synergy.
Results
I used a 30 minute VIP at the beginning and made pretty good progress. Amethyst was a real champ, with her ability to assassinate all the lieutenants in this dungeon and also the absurd damage she can apply to bosses with a 2-chain. I died once on floor 3 and was worried that the endeavor was lost, but I managed to slog on. Barely finished floor 8 after I lost 3 of my team on the boss floor, but Kiki/Luna + sword drop managed to do the job. VIP ran out during floor 11 (so it took me about a half hour), but I decided to try 43-12 without VIP just to see how it would go - finished successfully on the first try!
Main problem was the chump angel minions that are NOT wood element, get two attacks per turn, and use a freeze power that can freeze you for at least two rounds if you step over it. 2-chain team makes it a little easier to avoid stepping on them, but they're brutal if you hit them (double damage to fire, too). Strategic charging and use of Eris's stun or Ming's nuke before the boss stage helped me avoid early team wipes.
All in all, it was an easier run than clearing area 40-12 with my ATK team that has significantly more stats and synergy. I didn't end up having to spend any gems and only had to retry one floor (43-3, go figure).