Need help with Yorick math, he may have an issue

Touch of the Maiden comes up every 2 seconds. Yorick attacks an opponent to activate the effect, putting it on cooldown for 2 seconds. He then attacks two more times after that. If his attacks are slower than one attack per second, the mark should be up in time for the second followup attack.

Apparently, this only works up until around 0.92 Attack Speed and beyond, where it can take three autoattacks.

0.71 AS gives: Proc, Hit, Proc 0.82 AS gives: Proc, Hit, Proc 0.92 AS gives: Proc, Hit, Proc OR Hit 0.96 AS gives: Proc, Hit, Hit

Can someone explain to me why it cannot activate this effect when the two attacks take longer than 2 seconds to complete?

This is important because Yorick hits 0.96 AS with Triforce at level 7, and 1.00 AS with Triforce at level 10.