This question deals with the procedures on YK itself, not the 10 days of repentance.
Rambam (Hichot Teshuva 3) says that YK is dedicated for Beynonim, i.g. those whose merits equal to sins. Further he claims that the final verdict of YK is based on weighing one's merits vs sins and not how hard one davens on Yom Kippur.
My logic says that the whole YK day must be dedicated to maximizing one's merits thru performing as many Mitzvot and especially Torah learning, as the greatest Mitzvah of them all - Peah 1:1 as one can, just as Rambam prescribes for the 10 days of repentance.
Instead, we do almost "nothing Halachicly valuable" on Yom Kippur, besides the one-time Mitzvah of Viduy (Teshuvah) and the regular Teffila amd Krishm"A (as for Rambam). No obligatory Torah study, no Tzedaka on YK, no procreation etc.
Why we don't try to maximize our merits on Yom Kippur through engaging in Mitzvot and Torah learning?
NB: Do you think opening a Kolel "Yom Kippur Torah" for those who can't daven for 6 hours straight is a viable option?