On a scale of 1-10,
-- women are usually desperate to make it into the very comfortable 4-6 range
-- 7-8 range is a nice bump
-- 9+ is usually no advantage over improving in other aspects.
Discussion
And women usually have a range of ±1 or 2 that they can calibrate.
Ideal is probably a 6, as she can pull out all the stops and squeak past a 7 or even an 8, but can go unnoticed and blend in, if she wants to.
It likely to be true for any "property," e.g., for physical strengths, it not great to be weak, say below 5, it's pretty great to be string, 7-8, but super strong, 9+ takes inproportional amount of effort and is simply not worth it. Same goes for apartment cleaning, I like the 7-8 area, but would not really want to do or even live in the sterile 9+.