Re-writes come in all shapes an sizes. They're reflected in new drafts that start on page one and overhaul the entire script. They can be the addition of some scenes, removal (or combination) of characters, or smaller edits to streamline action and dialogue. Re-writes can be everything between all of the above. They can also be, as my producer says, "micro-surgery."
Ideally, most writers get to the micro-surgery stage. Here, they're not implementing major changes - not to characters, the story, or the structure. Rather, they're focusing their attention on a handful of notes intended to improve the story by beefing up certain elements that might not be playing as successfully as they could or should. Perhaps a character is pining for his long lost high school girlfriend, but their relationship isn't as strong as it can be. A few well-placed, tactical extra details could add meat to their history and really connect the audience to the fact that this guy is still in love with Debbie Sue. A glance at a girl who looks similar. Accidentally calling someone by her name. A photo stuffed in his wallet that's caught only with a perceptive momentary glance. While readers might know that he likes her, sticking a few small, organic details like those in could really lock the audience in, emotionally.
Same thing if your protagonist really wants to open a pizza shop, for example. Stock his home pantry with pizza sauces - or better yet, have him stirring a pot of his own when his friend comes by for their evening poker night. The small details that can hone the important elements of the script can up the stakes, remind the audience of why the characters are doing what they're doing, and drive the emotional resonance home. The way to implement these isn't through "band-aid solutions" (another of my producer's sayings). It's not the goal to just stick something on, to which the reader will think, "oh, this is an obvious flashback of Debbie Sue because we're supposed to care that they broke up against our protagonist's wishes." A sloppy fix will appear to be just that - a sloppy fix that's convenient, false, and unnatural in the script. Rather, the goal is to do micro-surgery; figure out ways and places to up the stakes and the impact of certain beats, and - most importantly - how to do so in ways that seem entirely organic to the story.
That is what I've been doing all week. Micro-surgery. For the most part, I think I managed to be pretty successful, too. When I went through the full script, looking for areas where a detail would fit naturally, distinguishing the right places from the wrong ones became pretty easy. Not only easy, actually; it became obvious. Of course there would be no thought of his beloved dog here - there's nothing to bring the memory into place, and he's dealing with something much more immediate at the moment. Here, however, it's almost hard to believe I didn't have an empty dog food bowl sitting in the corner. How obvious (and organic) an addition.