well my secret is that the brushes that i use most often at any time tend to switch up. a brush that i love and is my go-to can suddenly feel boring and i need to browse the asset store for a new toy to play with. but as for how long i mess with them i just do a few scribbles and test sketches and if they Feel right that becomes my main brush for a while. also idk if i really mess with different types of styles moreso my style kind of evolves as i take in different ways of drawing