he's done it countless times before and has annoyed me on many occasions with comments and frankly I'm not surprised he is now suspended, he's one of the most patronising people I've ever seen on any internet forum, let alone here.
He wasn't patronising to anyone. He made a perfectly reasonable and accurate statement which was then taken to mean something else and dragged out by others.
David has a good deal of knowledge compared to most, and isn't shy of sharing it. People do seem to be fond of arguing with him though.
To the OP, there are a lot of threads on processing/editing already that may be of use to you. David covered most of it in his first reply as well, the number of shots you take and the amount of processing you do really is horses for courses.
At an average event, I may shoot 400-1,000 frames, and deliver somewhere close to 50% of those to the client. I rarely delete on camera unless I, A. have time to stop what I'm doing and review images, and B. am 100% sure I don't need the file based on the little LCD screen and my knowledge of what happened when I took the shot.
I shoot quite a lot because I'd rather have the shot to choose from than not. There is also (despite me being half decent at my job) a fair element of luck to the results

no matter how many years I shoot the same event, with the same performers, venue, AV crew, etc, etc. there is no way I can guarantee 100% getting the exact best pose and expression from a performer flying through the air in the dark and time that to coincide with a computer generated random spot lighting system being fired at her from 360º, whilst hoping that there isn't a big piece of confetti falling from the ceiling blocking her face at that split second, and then time all that with the actions of 30 other performers who I may want in the frame as well... So, I will take a series of shots and then pick the best one to process.
Processing an event I probably spend a few seconds on each file at first, and then go back and work on some more in-depth tweaks as needed once I've made my selection.
