Should you plan to stop resetting, you can estimate the time you will need for Lin by looking at money income.
Skill max was raised several times. As the game is designed, new Girls are always to be excpected, along with increase in Warp Maximum.
Prefarming has its limits, bc there will be a warp increase. The cash demands previously grew in groups of three Girls, with Lin the group now is four. So either they abandoned the grouping and "only" increase the next girl by x2 to x4 or the next girl will have x20 or similiar, like previous increases.
Tattoos do.