(Click pics for full size)
I generally avoid some sorts of practices, if I roof over an existing composition roof I remove the preceding roof's hip and ridge shingles and I do not wrap field shingles over hips and only one side over a ridge. The "roofers" who went after this thing not only put on too many layers of comp, they wrapped over the hips and went over the preceding hip shingles - the result was well over 3 inches of shingle and a forest of nails.
The above picture is from the only small roof section with only 2 layers of composition over the wood shingles. There are two methods of dealing with a wood shingle roof, one is to take off all shingles and put OSB or plywood over the skip sheeting (wood shingles were applied over planks spaced a couple inches apart) or if the wood shingles are in fair shape and the customer doesn't feel a need for a smooth roof to go over the wood shingles. Going over wood shingles with 3 tabs created an obviously lumpy roof and the tabs sealing down was somewhat questionable, architects have performed well for me over the last 20 years in this application. So you understand, redecking very nearly doubles the cost of the roof for a fairly minor improvement in performance.
I thought I'd managed to get the cell camera level to give you a feeing for being up high on something steep, not such a good job of that. You'll just have to tip your computer until the trees in the background are upright.
It is a fact of life that construction contractors are considered rip-offs by a large percentage of consumers and that those engaged in manual labor are over-paid ignoramouses. Next time somebody comes up with that kind of crap feel free to ask if they'd do this for any amount of money if they even began to have the physique to do it. I'd bet not, and I've heard from enough people who've tried simple projects that they'd never ever do it again. This has been hard filthy work and I'm not complaining about that - I bid the job, after all - but I do get pretty tired of people acting as though only their level of education qualifies them for decent income.