I have cheat sheets for each shop report. Makes my report time go quicker.
I calculate shops on a 2:1 ratio. My general rule is that it requires 2 minutes of report time for every 1 minute of shop. 20 minute shop = 40 minute report, so 1 hour total. My hourly minimum is $25. So a 1 hour shop, for me, needs to pay at least $75 to be worth it.
The waiting game (for bonuses) works for me because of where I am, but may not work for you if you have good shoppers in your area willing to do it for less. I find it pays off... I get the same amount of money for way less work.
There is one car shop I'd do for $25, but that's because the report only takes me 20 minutes. Plus I like the car.
------------------------------------------------
Plan the work. Work the plan.