Isn't it usual that it is 10x for every inch of aperture, depending on the quality of the scope hence there is no definitive answer.
My 120 triplet will go 15x or more per inch on good seeing whilst an acromat 8-10
I see no reason to "push" it, for what reason if the image is degraded
Too many factors you can't account for including peoples eye site and eyepiece quality on given scope, Experienced planetary observers use 20x to 30x per inch of aperture to see the most planetary detail.
https://www.skyandtelescope.com/astr...magnification/