Many would assume that the top speed you can run a mile at has little impact on how fast you can run a marathon or even an ultra marathon.
However your top end speed does indeed affect how comfortable you are at longer distances.
The 100m and 200m events are considered maximal efforts. That is about as long as a person can sustain their highest power output and speed. Anything longer is considered sub-maximal.
In a 1500m event you may average 60% of your maximal stride power of a 100m race.
In a marathon, that number is closer to 40%.
Lets say at maximum speed you can run 10 meters per second, but you improve that to 9 meters per second. A 10% improvement. That speed increase will also benefit every run from the 200m to the 100 mile event.
Max King has won the JFK 50 miler, and the 100k Ultra Race of Champions, but also has a 2:14 marathon PB, an 8:30 3000 meter Steeplechase, and a 4:30 mile. In an interview for Trail Runner Magazine, he said, "Because I've got a top-end speed of a 4:30 mile means that a six-minute pace is much more comfortable."
The same applies to you and whatever your goals may be. Perhaps during the winter, take a few months and work on your mile time. Lets say you drop your mile personal best to 7:00. That will make an 8:00 pace feel quite comfortable for your 5k/10k races!