It all depends on what you are doing..
I seldom use pocket screws on 1/2" material.. maybe only used 2 dozen that size in my lifetime.
Very few on 1.5' material too (maybe 100 screws)
I've gone through thousands on 3/4" material..
I'm just trying to save you some money .. If you do buy an assortment, start with small size boxes, other than the 1 1/4" length (that's probably what you will use the most, but maybe not lol)