IIRC correctly, Jewish law forbids rolling a Torah back untik you reach the end of the scroll. As you need to read a specfific Torah portion for Rosh Hoshanah that would require yoiu to roll back the Torah, you need a separate Torah for that holiday (the Jewish new year for the Jewish impaired). This is the case for another holiday. I shamefully cannot remember which one. So, three Torahs are actually required. One primary for use in weekly services and two for special holiday use. This is to be expected from a religion that requires a set of meat dishes and utensils, a separate set of dairy dishes and utensils, and another set of each for Passover.
ETA
I miss ZevSteinhardt. He would give a jolly, learned and definitive answer with cites from the Talmud. I also miss pictures of him and his family baking hamantashen.
Because this whole digression is really a hijack of the main topic, I’m hiding the quote from that link and my comments.
But perhaps there are others in the discussion who find it interesting.
details about handling Torah scrolls
Before the reading, it is the task of the gabbai to prepare the Torah scroll at the proper place so that it will not have to be rolled there in public, because it is disrespectful to compel the congregation to wait. Generally there is no need to prepare the scroll, since the reading is conducted according to the order of the weekly Torah portions, and thus the Torah is opened to the place where the previous reading left off. However, on Festivals, Rosh Chodesh, and fast days, the Torah is read out of its usual order, and it is necessary to prepare the Torah scroll ahead of time. Afterwards, it must be rolled back to the order of the weekly Torah portion.
And i do know congregations with fewer than 3 scrolls, some pretty frum.
But as with most matters of Jewish law, there are probably different customs in different communities. And following three customs of your community is required.