Manyu: I personally don't farm the weekly Manyu maps anymore, because RNGesus seems to like never giving me level 100 Manyu when I do them. Lately I've been either slowly accumulating them from the daily missions/gathering, the occasional 80 Stam SG that comes when I'm grinding perma-reissues (These seem to be rare compared to raid boss spawns so this has been a bad source of them in terms of quantity), purchasing them with Life Gems (Grinded a whole bunch of these and had some extra leftovers last event), and 2-1/Beginner SG farming when I've got an hour or more to kill. I've got a lot of Unevolved/Newly evolved girls so this seemed like the best way to get Manyu in bulk without totally destroying my leveling (I'm still a newbie, so getting a level up for a larger stamina pool is still on my mind when I prioritize what I should be doing), and as I've said, I'm an inefficient gold user, so using 10 level 5 Manyu on a level 50 girl really doesn't bother me.
I tend to leave non-event 5 Star girls at level 50 evolved because I haven't decided yet which ones I want to throw my Ampies at after my 6 Stars get finished up. The exception was Hypericum, my first event girl, who got dibs on my first 300 Ampies in commemoration. While I probably should be leveling 4 girls to max at a time, I've been lazily throwing my Manyus at pretty much any girl who catches my eye in the Upgrade screen with two exceptions: Fatsia, to get an evolved girl to level 70 to maximise helper usefulness since I don't plan on Ampie-boosting her booty any time soon, and after that Daisy. More bad habits, I guess. XD
Dragons: This is the one thing I don't mind being a little more conscientious in farming. I tend to keep 6 Ancient dragons of all the colours and 4 of their level 20 variants at any given time in my inventory- just in case. As I previously mentioned, I used to be evolution-crazy, so this is a habit that stuck from when blowing a whole day of stamina + saved stamina from the day before was a regular thing. With most of my in-team girls being evolved now and fighting over Manyu to get me to the point where I can reliably run any map without girls dying, I ended up hoarding a bunch of them. Gotta say though, never NEEDING to get a good dragon run is a relaxing thing. I do admittedly have great luck farming them - getting 3 Elder Dragons in a single run was more or less a once a day thing, and I don't think I've ever gotten a 5 level 5 or 20 Dragon run doing the 80 Stam map. RNGesus more than makes up for the Manyu map for me here.