The more parts you need to carry the better organized you need to be!
I am definitely a neat freak.
Years ago ran a repair shop for a mine. Our warehouse was maybe 200' from our shop. The warehouse was 40' wide by 125' long and had 3 employees. We had $1M in electrical parts and another $1M in electric locomotive parts. I had 12 electricians in the shop who spent an average of an hour a day each in that whse. looking for parts. It was a tall building, had them build a mezzanine floor and moved all our parts upstairs, we found items we didn't even know we had, organized, and listed into computer - when done only 1 hour per day - total - spent in warehouse getting parts/supplies. The warehouse also cut back to 2 employees! We ended up doubling the size of the warehouse, had much better control over the inventory - and paid for it in 2 years with the savings in time spent looking.......