By looking at expected resource consumption of each farming method (which is fixed when farming Nova Medals or Platinum Medals, and variable for map clears), it becomes possible to mathematically determine which method would give you the T-Doll with least resource consumption. The infographic here provides a quick summary:
What exactly are these medals?
Dear Commanders,— Girls' Frontline-EN Official (@GirlsFrontlineE) April 24, 2020
Now we are bringing you a preview of the limited drops in the DJMAX collaboration! There will be a limited drop in each story stage as well as the corresponding EX stage, and we will also have a welfare system this time!#GirlsFrontline pic.twitter.com/1ElR8GxQyQ
While this system was mostly intended to give unlucky players a failsafe mechanism so they'll eventually get the T-Doll they want even if they can't get a lucky drop, it also gives us an alternative means of farming event-limited T-Dolls by clearing the easy stages for medals while avoiding the long convoluted stages that are difficult to farm.
This will, of course, not be efficient when the farming stages are easy to clear, but the DJMax Collab has two stages with easy medal drops and four hard-to-farm stages, making the conditions perfect for players to save a lot of time and resources by medal farming.
The only drawback is that farming this way takes a fixed amount of time, so you can't get lucky and end farming early on - but on the flip side, you also can't get unlucky!
How can I use this information?
Let's say a player wanted all six dolls in the Glory Day event, since there are no maps where it's cheaper to farm directly compared to the medal-dropping maps (E1-1 and E2-1), they should only farm medals (preferably with low cost echelons - 1HG and 1AR respectively).
Aside from those two, are two 4-star T-Dolls and two 5-star T-Dolls to buy. This means the medal count to farm (for players who need every doll) equals:
For players who read this on the day it was posted, there are 20 days left in the Glory Day collab - meaning as long as you farm at least x40 and x50 each day (20 clears of E1-1 and 17 clears of E2-1), you're on track to getting every limited T-Doll this event has to offer. Players who only need to farm a subset of the available dolls have even less work to do!
Should I medal farm in every event?
No, some future stages will be easy to farm from and are therefore more efficient than medal-farming. If you want to see more articles/infographics like this for upcoming events, leave a comment below!
Where does the 0.5% drop rate estimate come from?
It is based on the estimated drop rates from White Day and VA-11 Hall-A events, and so far seems to match the drop rates observed by EN players in Glory Day. Story events may have different rates.
I don't need any of the T-Dolls, should I medal farm for cakes?
If you can run the budget teams successfully, it'll cost about ~300 total resources to farm one cake (and a boatload of time to empty the 200 cakes from shop). This is a pretty good deal, especially for F2P players who don't have excess cake from whaling the dorm re-supply.