As someone mentioned, I think one of the very best advantages of having a shop (separate from your house) is the ability to lock it up and leave things where they are.
(For a solo owner)
Whether it's paperwork on a desk, something you're working on that's on a table, or a mower (in the middle of the floor) that is being worked on, being able to lock the shop up and have things remain exactly where you left them (sometimes for weeks) is almost priceless.
(With several employees)
Having a shop is still a huge advantage, but things will still eventually have a way of getting moved around when more than 1 person is working in the area.
I've had a 1500 sq ft shop for about 15 years, and now that I'm used to having it, I can't imagine
not having one. My shop is located on the same acreage my house is on, but is 100 yards or so from my house.
This distance between the 2 means the house and the shop don't interfere with each other, but, the shop is close enough to my house so that there is no driving involved on days that I'm only going to be in the shop. The lack of the cost of driving back and forth to work (on days I'm not leaving the shop) really adds up to a big savings in a year's time.
Good luck with whatever you decide to do! Stan