Roller coasters aren’t fun because they are fast per se; their fun actually comes from the changes. First is the long, slow climb, building anticipation. Then your stomach lurches as you drop and twist and launch through turns and loops, and your speed fluctuates, too, slowing on some hills, before lurching down again. Etc.

In games you utilize the principle of cadence to make sure that levels are constantly shifting in terms of pace, difficulty or even type of skillset required.