I think it would depend on what medium you were shooting in,your budget demands and the scope of the film you're making... if working with DSLR or M4/3 filmmaking, in theory you could have a great script, carefully planned out and storyboarded scenes, a small group of decent actors, well-chosen sets and well-placed lighting....and you could pull it off with two people, one behind the camera and one on the boom pole. Those two guys are going to have to have a basic knowledge in everything from lighting, sound, camera operation and editing. There is a good podcast on itunes (for free). Its Ed Burns talking about the Newleyweds and how he got back to basics with a very small crew, everyone took on more than one job on the set. Its called The Q&A with Jeff Goldsmith..pretty inspiring if you're a low-budget filmmaker.