I measure by the SF. Keeps me from making errors guessing a prop was to big, bidding and not getting the job or to small and under bidding and leaving money on the table.
Also all neigbors think they should pay the same as the guy next door but you can say exactly how much larger his prop is showing him why he has to pay a little bit more.
Knowing SF is needed to up sell fert and reseeding.
Easy to do with a wheel.
Easy to measure on google earth, and you can get SF from zillow.com. Though both ways have been off from time to time.
Though it's always better to walk the prop and measure with a wheel. Can't see the extra problems that will eat up time or measure gate opening exactly any other way.