yom kippur

The posuk says לכפר על בני ישראל מכל חטאתם אחת בשנה this is for you as an eternal decree to forgive the jewish people for all their sins once a year.
Why did the Torah write once a year only by יום כיפור? All the other holidays also come only once a year.
The gemara asks, why was the death of מרים recorded next to the parsha of parah aduma? To teach us that just like parah aduma is mechaper, so too is the death of a tzadik mechaper. Why was the death of אהרן next to the בגדי כהונה? Just like the בגדי כהונה are mechaper so too is the death of a tzadik
We see that we can have a day like יום כיפור- a day that's mechaper more than once a year.
The mishnah berurah says, that at least in the days between rosh hashana and yom kippur, one should do like the zohar says and before he goes to sleep take an accounting of his deeds & do teshuva.
There's a story told about the chafetz chaim one יום כיפור night. After everyone went home from shul, he stayed. One of his students wanted to observe him, so he hid under a bench to see what his rebbi would do when he was all alone. The chafetz chaim saw that he was alone so he began to make an accounting of everything he did the whole year, month by month, week by week, day by day, then hour by hour. After he finished his accounting he had one hour out of the whole year that he didn't know what he did with.
He started crying bitterly, rebuking himself, saying yisroel meir, yisroel meir, what's going to be with you? What did you waste an hour of your life on? Chazal say that you can acquire your world to come in one hour, & in that hour 'ה gave you life, health, sustenance, healthy children etc, how could you waste it!? That was the chofetz chaim, crying over one hour; what can we say........
On our question of why it says once a year,הגאון רבי יעקב חריף מוילנא explains with a mashal of a man who was very sick, who had to travel to the big city to an expert doctor. They rushed to get him there with no stops along the way, however, if he had an attack along the way they would have to take him to the local doctor to control it until they could get to the big city so that he wouldn't die along the way . Similarly, when the jewish people are going through the year, and the sins aren't too bad, when יום כיפור comes they do a wholehearted teshuva; then we can make it from one יום כיפור to the next. However, if the sins are very grave, then we can't make it straight to the next יום כיפור & we get sent a day with the death of a tzaddik or similar tragedy. That's like יום כיפור in the middle of the year to propel us to do teshuva. This is what the torah is saying, that now, on יום כיפור, we should do real teshuva so that it will be just once a year & we won't need any more days like יום כיפור. If we could learn a little from the chafetz chaim how to examine our deeds & account for our time, & not waste it on frivolous matters, maybe then we will make it from one יום כיפור to the next with no stops in between, and possibly the time we don't waste will be the hour that will grant us eternity!

Wishing everyone a גמר חתימה טובה