Personal Requests in the Amidah Prayer.

When is it appropriate to make personal requests in the Amidah prayer?

It is stated in Berachot 22: "Rav Yehuda said in the name of Shmuel, a person may ask for his needs in 'Shomea Tefillah'. Rav Yehuda, son of Rav Shmuel bar Shilat, said in the name of Rav, even though they said a person may ask for his needs in 'Shomea Tefillah', if he wishes to say at the end of each blessing related to that request, he may. Rav Chiya bar Ashi said in the name of Rav, even though they said a person may ask for his needs in 'Shomea Tefillah', if he has a sick person in his house, he says in the blessing of the sick. And if he needs sustenance, he says in the blessing of the years. Rabbi Yehoshua ben Levi said, even though they said a person may ask for his needs in 'Shomea Tefillah', if he wishes to say after his prayer in the order of Yom Kippur, he may." The Shulchan Aruch, Orach Chaim, Siman 119:1 writes: "If he wishes to add in each of the middle blessings, related to that request, he may. How, if he has a sick person, he asks for mercy in the blessing of 'Refa'enu'; if he needs sustenance, he asks in the blessing of the years. Rema: and when he adds, he begins with the blessing and then adds, but does not add and then begin the blessing (Tur, Siman 607); and in 'Shomea Tefillah' he can ask all his needs, as it includes all requests; and according to Rabbeinu Yonah, when he adds in the blessing related to that request, if he adds it for all Israel, he says it in plural and not in singular, and does not add except at the end of the blessing and not in the middle; and if he asks for his own needs, such as if he has a sick person in his house or he needs sustenance, he can ask even in the middle of the blessing, and he should ask in singular and not in plural; and in the blessing of 'Shomea Tefillah' and also at the end of the prayer, whether before 'Yehiu Le-ratzon' or after it, he can ask both in singular and in plural, both for his own needs and for the needs of many." The Mishnah Berurah writes that one should be concerned with the opinion of Rabbeinu Yonah, and therefore in personal requests at the end of a blessing, one asks in singular. And what is written that at the end of a blessing, specifically about the past and not about the future, is explained in Mishnah Berurah, Subparagraph 1: "See in Pri Megadim, who writes that specifically if he had, and also in sustenance specifically if he needs sustenance, but he is not permitted to ask for mercy in the middle blessings about the future, that he should not become sick, and that his bread should not be lacking, and the like, unlike in 'Shomea Tefillah', even about the future he is permitted to ask." And what is written not to lengthen in 'Shomea Tefillah', is explained in Shulchan Aruch, Siman 119:2, which writes: "There are those who say that when he adds in a blessing for the needs of an individual, he should not lengthen" and Mishnah Berurah writes there, Subparagraph 12, that even in 'Shomea Tefillah' one should not lengthen. And as proven in the words of the Gemara, that specifically after the prayer one can in the order of Yom Kippur, but not in 'Shomea Tefillah'.