It really is not quicker to do it room by room because once you have decided what to keep you really do need to know where it is going to go.
The best tip on here is up thread, where someone has linked a category list broken down minutely. My daughter is unable to do it in the order that the book says for the same reason, lack of time and space.
I sent her the list and she just picks one of the mini categories and does them in a convenient order.
Like the book says, keep things which are the same in the same place. Most of us have things all over the house.
If you start with clothes, try to do, pants, tights, vests tops, then nightwear. It will take 4 days, 30 minutes a day. I honestly believe that this will get you on the right track. I never thought I would throw out so much underwear, that I would fold pants, or that I would get a spark of joy opening my undies drawer.