It is extremely rare to see them come up to exactly 90 degrees and why I spend some time in that area to make sure they do.
Related, I just got in a troubled 7037262 carb yesterday that went to two different builders before it ended up here. It would take several pages to list all the issues I found, but I chuckled when I check the secondary throttle plates as they were rolling about 15 degrees past where they should have been and two "builders" didn't catch it nor did they catch the fact that the secondary throttle plates aren't sealing well in the bores either.
That's another common problem I see that creates all sorts of issues even if the rest of the rebuild/restoration was done well..........Cliff