One of the tefillos that especially colors and characterizes this time of the year is אבינו מלכנו. Though its basis is ancient, based on a gemara, it was further developed as time went on, and divergent customs developed around it in some places. As with tefillos in general, it is highly recommended to learn more about it, to make your prayer more meaningful, and hopefully more effective, and to leave rote prayer behind (hopefully).
The renowned siddur Avodas Yisroel, as is its wont, sheds significant light on the prayer. It informs us that the amount of supplications starting with Avinu Malkeinu therein varies greatly between Sepharadic, Ashkenaz, and Polish versions, from 29, to 38, to 44, respectively, with a total of 53 different versions existing. In addition, there is a difference in sequence between nuschaos as well. One difference in sequence which caught my attention in particular, is that while in nusach Polin (Eastern European), אבינו מלכנו החזירנו בתשובה שלמה לפניך, asking Hashem to bring us back in complete repentance before Him, follows lines such as א”מ סלח ומחל לכל עונותינו, א”מ מחה והעבר פשעינו וחטאתינו מנגד עיניך, א”מ מחוק ברחמיך הרבים כל שטרי חובותינו, in nusach Ashkenaz it precedes them. That seems to have significant logic on its side, as at the least, praying, yearning, and striving for repentance (hopefully followed by actual repentance), should lead the way, rather than asking for an outright, unequivocal pardon from above first (although it is true that part of repentance, the admission of sin, was already addressed by the first line, אבינו מלכנו חטאנו לפניך).
Another difference in אבינו מלכנו between nusach Ashkenaz and nusach Polin, is that nusach Ashkenaz says it during aseres yemei teshuvoh, but not on a regular calendar taanis tzibbur in other parts of the year, while nusach Polin, in a relatively recent development, does. Update: I looked at a Sepharadic siddur and it seems to be the same as Nusach/Minhag Ashkenaz here, meaning that Avinu Malkeinu is not routinely recited during a regular taanis tzibbur outside Aseres yemei teshuvoh.
May we be zoche, in the zechus of עיון תפלה, analysis and delving into our prayers, which we are taught (as said in tefillas Shacharis) is one of the things שאדם אוכל פירותיהן בעולם הזה והקרן קיימת לו לעולם הבא (sounds like a great investment!), to more meaningful and spiritual davening, תשובה שלמה, and a שנה טובה.
Thanks to all for their support.