I use one stem all the time and it gets a pipe cleaner run through it after every smoke. When it comes to bowls of have 6 that I have dedicated to certain styles and when I switch up my "style" I clean out the stem with everclear, grab the right bowl and go. Even though I have multiple stems and bowls I like the one stem because it has my teeth indents and fits me perfectly and I've settled on 6 Hyperboles because they hold the perfect amount for my smokes.
My "styles" are as follows:
Burley Blends, Deer Tongue Blends, Latakia Blends, Light Aromatics, Perique Blends and Straight Virginias.