I don't have a crew, but have tried to do the math on adding full time guys or how many lawns I need to have a crew.
During the summer I have hired the same high school/college guy the past 4-5 years. He knows exactly what to do and I don't have to tell him anything. What I find is that we aren't that much faster than me by myself. We hustle and not much lazy time.
It just shows you that as owners we work harder than employees do. On the flip side I am much less tired and have more time for side jobs with a helper.
As I've considered a crew the hard part for me to figure out is just how much money I want to put in my pocket when all the expenses are done.