On question 1892 you mentioned that Horav Miller rules that a person who is davening Maariv on Motzei Shabbos 50 minutes past sunset, and his custom is to prolong Shabbos for 72 minutes, to say the Havdala of Ata Chonantanu, even if he still keeps the prohibition of doing work until that time has arrived. Why is it permitted to say the above since it contains a Tefila for the personal needs of the coming weekdays we are about to start and those should not be said on Shabbos?

Actually there are several prayers we recite during Shabbos for our personal needs. Some examples are 1) Tazileni Meazei Panim after the brochos of the morning. 2) Sim Shalom. 3)Elokai Netzor after Shemone Essrei. 4) Yekum Purkan before Musaf. 5) Birchas Hachodesh before the beginning of the month, and others. Horav Shlomo Miller’s Shlit’a opinion is that only the reciting of private Tefilos on personal needs is avoided during Shabbos to avert thinking of those needs and getting involved in the worries and pains they reflect, that is forbidden during our day of rest and enjoyment. However, the Rov maintains that when those Tefilos are printed in Sidurim and all say them, they are not part of the above injunction. The same would apply to the the prayer included in Ato Chonantonu.