I’d say different picks are useful for different applications/stylistic requirements/tonal preferences. Speed can be a factor when choosing a pick, although once you’re Paul Gilbert, it doesn’t really matter, a .53 will do just fine. I find the biggest differences aside from thickness, is the bevel, the point shape of the pick and the type of material used. It’s definitley worthwhile having a variety of picks of all shapes, sizes, materials and thickness available is useful, both for adding a new level of challenge to your routine, as well as another tool to your toolbox.
Or just get a .88/1.0/1.5mm jazz III because