I think
Seattle Forrest is on the right track.
As for improvements from sprint intervals, I'd like to hear the results that
tempocyclist gets. Personally, were I to try to make a difference for myself, I think weights would be what I would try. Though I definitely haven't done any structured training to improve my sprint, that doesn't mean that I don't frequently push my short term limits. In friendly sprints, be it IRL or on Zwift, I do *try* my hardest on short duration efforts with some frequency, even though I suck at it. I just seem to lack the leg strength to turn the cranks above 700 and some watts.
One thing I did learn, on brief Zwift efforts, is that I'll get my highest watts not by turning the hardest gear, but by turning a somewhat easier gear at much higher cadence.