I've always used my eyes. lol I walk in to a house... I know how long it takes to clean it so I bid accordingly. Back when I bid commercial I'm not sure they had much software on that sort of thing. I did a walk though, took notes and figured up a bid. Then I delivered the bid in person.
I was never good at commercial bidding because I bid too high. I'm not sending anyone to a job that only brings in $35 even if its for a small office and only takes 45 minutes. I do have 1 office now that takes an hour and I charge $75. Back in the day we had a 13000sf medical building that took 3.5 hours to clean and I charged $140 per night, 5 nights per week.
Why do anything that pays less than what residential brings in was what I always went by. I doubt when I go back to having employees in August that we will have any commercial jobs other than the 1 office job I currently have.