Usually you always shoot at least two takes, even if Take One was perfect, just in case the shot gets ruined in the lab or something. It's called a "safety" take, as in "we need a safety". Now, you don't always need to shoot a safety if you've got one perfect take and a bunch of partially-good takes from which the you could cobble together a replacement should the one good take get damaged.
In terms of coverage -- how many angles you shoot of the scene -- that's a creative choice modified by the amount of time you have. You may decide that a scene will play as a "one-er" ("oner"?), all in a single shot, but then you're sort of stuck with it, and you'd need to get at least two good takes because you won't have editing to piece together the scene if there is only one angle (unless you can justify jump-cuts.) Trouble with one-shot scenes is that you can adjust the tempo of the scene in editing. But sometimes that's OK -- it even be the best way to shoot the scene. You just have to be aware of the problems with that approach.
Sometimes when you're rushed, you shoot a scene in two set-ups, the second one, usually a tighter angle, mainly to allow you to cut-up the scene if necessary.
Staging and editing is a little like music -- the emotional tone of the scene sort of guides you as to how "cutty" it should feel, versus how "flowing".