You asked if each Botox treatment makes your voice better than before. In a matter of speaking, it might BUT I need to explain how.Each person reacts to Botox differently. It may take your ENT four or five shots to figure out what your optimal dosage is.
You can help the ENT by keeping a log and noting when your initial breathiness goes away and when you need another shot.
You'll know when another shot is needed because you'll find it harder to get the words out. When that happens, and it will,
get an appointment for another shot.
With your history of several shots, the ENT will figure out what dosage is best for you. So over time, in this way, your voice may improve from where it is today.