Since i'm not sure what to call it, a "prayer mode" here is the style of the tunes used. I'm not exactly sure how to describe the tunes. Either you know it or you don't.
The traditional mode for Yom Tov davening among Ashkenazim (at least during the day) seems to have an "amein problem". Namely, the congregation begins saying amen before the chazzan finishes the bracha. This is a problem (Shulchan Aruch, Orach Chaim 124:8).
With this in mind, where did the mode originate, and why is it used so much? Also, did it originally start this way, or has it been corrupted over the years?
FWIW, some chazzanim will cut it short to prevent this problem.