I have an extinguisher at each bench in the shop. Mounted on the front of the bench...it kinda sucks to reach over a fire to get an extinguisher.
Also one at the shop's front door. And in each vehicle....jeez, I think I have a problem.
These never move unless there is a fire. I have a milk crate full of small/medium extinguishers that can be taken to work areas...wherever I'm welding, down in the grease pit, etc.
Don't forget to turn your powder type extinguishers upside down and hit them on the bottom with a deadblow to keep the powder loose. The years go by quick and that stuff settles on the bottom.