Generally whenever I personally talk about a shooting ratio, I am not just talking about the number of takes of each shot, as that wouldnt help me figure out how much film I would need for say, a dialogue scene with two people, unless I am shooting it all in a master shot. If I have a master, then a close-up of each person, each running the entire length of the scene for one take each then I have a 3:1 ratio already. If the scene were exactly a minute, I would have shot 3 minutes of film to cut into a single one minute piece. This doesnt include any cut aways or alternate angles I may need. If I say I am shooting 1:1 with one take on each shot without taking into account how many different angles I may need (or want) then I have no idea how much film (or tape) I will use.
Of course if I have to keep to a 2:1 ratio on this scene I can selectively film on each angle to try and keep as close to that as possible, which makes the math harder but the principle the same. This also means I need to have a very good idea of how it is going to cut together in the end, as I am stuck with some of the choices I have made. This happened once on a film I shot in college where we were running low on money and a decision was made to shoot the first half of a scene with a master and no coverage and then second half with coverage and no master (deciding at that point that we would move to the coverage when the scene got more intimate). It didnt come out horribly, but the editor was not to happy with not having the option to cut when he felt he needed too and the scene honestly could have used it.
As far as the one take method for a skyline or someone running down an alley, one take maybe good enough, but Ive been bitten by that one as well where there was some unnoticed problem which you are now stuck with. A second take doesnt mean that the problem will always be gone (like bad lighting, framing or focus), but sometimes its just that one person in the background making quick and obvious eye to lens contact or something else that just goes unnoticed at the time but may show up later.
Jeff Clegg
NH, DP