Botox depends on the individual
25 units can definitely be helpful to most patients, however, everyone is different. I have some patients that require 35 units to the glabella and anything less results in significant persistance of the lines. So while 25units is a great go to dose, it may not be what you need.
Furthermore, where can depend on each patient as well. some patients recruit from farther out on the forehead laterally for muscle movement, while some people are much more central. ...