This relates to an existing discussion you may want to review.
In general, the ERG From Sprints run a way quickly, so the first 3-5 seconds are kind of the important part, but adding the ability to control that fast spin in the latter half (of the typical 10 seconds sprints) is worthwhile as well.
These Form Sprints are common in workouts like Pettit, and others that are often around 60-70% of FTP.
You can find more by going to the Workouts section on the web, and searching for “form sprint”.