Luzid at 2009-11-30 19:20:17:
Sequencing helps immensely with focusing scene writing. Since every sequence is in effect a mini-movie that (with the others) builds the whole story, every scene in a sequence must work in both the sequence and the overall movie. Everything has to be justified. The beginning/middle/end structure of a story is fractal within any screenplay -- it informs every decision. I think a great scene expands on this with every beat.
That's why "something compelling happening" (in context of the overall story) is the key component of every great scene. Without a memorable event that fits perfectly, the sequence won't land with any real impact, and the overall movie won't feel connected and interwoven thematically, but rather episodic and disjointed.
A great scene strengthens the structure by remembering its purpose.