Is the effect of Botox cumulative?

[Deliheaven]

I appreciate that Botox wears off after a few months but does having it consistently mean that it takes longer to wear off?
I’ve had my first Botox in between the brows to relax my face (constant frowning giving me headaches) but I can see and feel it’s wearing off after about 7 weeks. I can’t afford to have it done every couple of months but if I persevere with it, will it start to take longer to wear off?

Some people develop antibodies to it , and then it doesn't work as well. Usually the effect does build up as the muscle becomes weaker and weaker through not being used, but each time you have botox the effect can be different, you never really know how the person will react to it.