Why on shabbos is ashrai said before returning the sefer-torah and on weekday (nusach ashkenaz) afterwards. This cannot have to do with kaddish tiskabel since this is also done on rosh chodesh where ...
Using an Israeli sidur (prayer book) nusach Ashk'naz recently, I saw that it had "Sim shalom" for mincha of Shabas (including Shabas yom tov, but not weekday yom tov), even though it had "Shalom rav" ...
In the birchot keriat shema of Shabbat morning, we add a number of pesukim in the beginning, and we switch the piyut of קל ברוך גדול דעה for the piyut of קל אדון. But all the pesukim said on a weekday ...