Controlling pace is important to creating and dispelling tension in a story. For example, having a slow pace that ramps up over time could build a crawling sense of dread. The pacing could also help to establish a character’s mindset. For example, having the pace be very quick could show a character’s franticness/urgency. In terms of pacing involving time and not a series of events, this could also affect the believability of a story to the audience. For example, if a romance story took place over the course of two weeks, it might be hard for the audience to believe that the romance is real or warranted. It could feel like “instalove”.