Picking the correct timing for the cure time with the job size is almost an art in itself. It’s unlikely one can figure it out without a lot of experience doing it and most folks that don’t do it for a living won’t do it often enough to acquire that experience. It’s a lot of hot mud waste and back and forth trips to the hardware store that’s exhausting for busy folks that have another full time job.
I used a drill with a mixer from a hand blender plugged into it. Made it really easy to make a batch that filled the stainless steel mud box I am using. Even being totally untrained, getting that onto the wall in under 40 minutes was easy. Took a bit more mixing and batches than a pro would take, but all in all... it wasn't nearly as hard as you're making it out to be.
