I agree. It's still unclear. They'll have to exempt event girls at first if the coaching is a new feature. Two weeks of coaching would have pushed any of them well past what was needed in the xmas or spring events.
I have a little more than 5% difference between a girl I coached before and the best girl. Each of the individual stats is higher on the best girl, though not by a lot on one. Still not able to coach them again. I get the "work on your best girl" message. It could be a one shot deal, too. It's hard to say when they give so little info on these things.
That would not be a problem. The spring girl was blocked from doing normal challenges, no problem blocking a new girl from coaching, while still being the active event girl. Oh, and they now do no longer open their own Get Clean page. Previously, Mistlhoe and little Miss Sunshine could open that page by clicking below the TV. And winning with them does not open it, too. But I do not know, if it was previously possible to win and get trophys with them.
That sounds better. If it were a one shot, you would not get a message like "work on your best girl". That indicates a threshold. Other possibilitys were a cooldown, the said one shot, buggy implementation with all the clothingbonus and inherent girl bonus and whatnot.
But with that message, I say threshold. And there are several ways to do that, of course. All base stats higher, sum of base stats higher, higher in absolute numbers, higher in percent of number, combination of several aspects, counting in stamina somehow etc.
Should the threshold be around 600k difference in sum of base stats, my guess would be 14 days worth of training is the threshold - since it takes 14 days to coach an untrained girl.
A threshold was my first thought as well. I doubt they bring in stamina since my best girl's is over 3x the other's. I do hope that it is a permanent change to the game. It makes the newer girls more obviously useful for something besides adding to the player stamina.
They could bring in stamina with relative practise time. Coaching is practise. But once over 200 stamina, there would not be a great difference.
My guess at the moment is, they have a minimum coaching time. Like the 10 minute 1 hour and 4 hour options. You cant train the 4 hour option for only half an hour. So, what is the minimum coaching time? It is reduced, if the trainee has higher stats. But is this linear or an arbitrary table.
I have not many trained girls. Most have 14 days as their coaching time. But two of them have only 13 days and 20 hours. So if it is linear, they might round to the nearest 4 hour point. So you might just need to have (14 2/24) / 14 or (14 4/24) / 14 better stats than the trainee. But if you have already a 5% difference, the minimum coaching time is propably a day or longer. That would be 15/14 or 7.2% in base stats.