$0 for ground????????? This is about the most outrageous thing I think I've heard! That's ridiculous! It takes a LOT of work and money to get even a Private Certificate. Now pile on an Instrument, Commercial, and CFI (as pretty much the bare minimum to teach) and you're talking a CONSIDERABLE amount of work and money. We're talking tens of thousands of dollars, literally. And who could count the time spent studying. It is absolutely proposterous for an instructor to provide a service (ground instruction or flight instruction) and not be paid for it. I absolutely cannot believe this! Any school that practices this is basically saying that ground instruction is just not important. I mean, if I didn't have a keyboard at my fingertips I'd be speechless!
As a general rule I usually spend about an hour of ground for each flight (not taking into consideration lessons that do not include an associated flight.) The breakdown usually consists of (rough estimates... it varies for each lesson) about 30-45 minutes of briefing first (to go over, in detail, what will be worked on during the flight, as well as for either of us to ask/answer any questions about the related material/flight). Then we fly. Then after we land, grab a drink and a pee, and try to dry some of the sweat up we debrief for usually 15-30 minutes (where we share evaluations/suggestions, ask/answer questions, and I assign study material for the next lesson.)
It is operations like the afore-mentioned that produce students/renters who act like you're doing them an injustice by charging them for ground. That's a great way to offer inadequate instruction. I personally would not want to provide a service that I worked extremely hard to be able to offer, and not be compensated for it.
Sorry for the strong words, but things like this have a very negative impact on the industry. How often do you find a College Professor that is only being paid for Lab lessons and not lectures. Just try to put it into perspective.
Happy flying all!