"...But Hourly Billing Works For Me"
"... but hourly billing works for me. Why should I stop doing it?"
It's true, hourly billing can offer the appearance of "working," in the same way that a car with a stick-shift stuck in 2nd gear "works."
You can get to the store and back, but...
If you want to take your business on a more profitable ride, the higher gears will get you there faster and with a lot less grinding.