We are still in Whitcomb's book (NOVEL SHORTCUTS), and this time I have chosen an exercise that she suggests involving the topic of how much of each you should have -- scene, summary, and reflection. A scene is spelled out action in real time. A summary, as the name implies, summarizes a span of time or events. Whitcomb differentiates between summary and reflection. The latter involves the protagonist reflecting about events that have occurred up to that point, and often, making a decision to take action. It can be difficult to know sometimes when to use each, but a scene should be used for meaningful moments that advance the plot. A summary can be used as a bridge to the next scene when nothing eventful takes place in between. A reflection is used to ensure that the protagonist's motivation is clear for why he or she will take a certain course.
Whitcomb suggests looking at your favorite author (or the kind of book you want to write) and seeing how that person balances scene, summary, and reflection since it can be challenging figuring out how much of each to put in. This one doesn't require any writing, just seeing how other authors handle this.