Rocks in a Jar

There's an old story about time management and prioritizing that I dearly love, not least because I've seen it repurposed several times.

The story, which I'm sure many of you are familiar with already, is the one about the professor who walks into class with a large jar. He proceeds to fill it with big rocks, and then asks the class whether the jar is full. They say yes. He pulls out some BBs and dumps a bunch in, so that they fill up the spaces between the big rocks. Is the jar full...