Back in the early 90's, I was one of the first to have Dura-Ace STI when they first came out. My coach was a track sprinter, he didn't like me shifting during the sprint. We worked a lot on spinning out a gear like track sprinters do. Then I went into my retro phase running Simplex retro friction shifters with Mavic SSC derailleurs with 8 speed. Raced mid 90's through the late 90's with that setup

Racing with downtube shifters requires being more aware of your course. Since I was already sprinting like a track sprinter, not being able to shift didn't really matter.