@Manzell Blakeley
It depends on truly what kind of shape it is. In my experience even when plaster is not crumbling, the walls are usually very uneven and ugly due to decades and decades of patching and painting. Depending on how nice of a condition you are going for it would require too much labor to make it look good so replacing is usually the way.
I have one MF that had old plaster walls with newer electrical installed OVER the walls through metal tubing. We rewired all of the units which required a lot of holes to run wires inside the walls, installed recessed lights, etc and then had a crew come in and laminate all of the walls with 3/8” drywall. Turned out absolutely perfect and didn’t need to remove plaster from 4000+ sqft.
Having a Sheetrock company install comes in very cheap actually. The bigger the job the cheaper the rates. If you were to do the full building it would be very cheap on a per board cost to hang, tape, mud, etc.