My first year I used a shop vac for everything, even the soot.
Thought it was smart. Saved time. Then one Tuesday in October, I'm cleaning a flue in a 1920s house. The filter clogs. Soot cloud fills the living room. Client's white cat turned gray. Took me 4 hours to clean their curtains. Bought a proper soot vacuum the next day, a HEPA model. Anyone else have a 'this is a terrible idea' moment that finally made you upgrade your gear?
Honestly, my version of that was trying to use a regular shop vac for drywall dust. Ngl, I'm pretty sure I'm still finding that fine white powder in my truck years later.