Q. If someone has problems on concentrating during the complete amida, after having kavanah on the first bracha, should he put effort on concentrating on other complete brachos, even if they are few. Or should he better focus on the end part of all brachos?
A. Poskim write that one should at least try to have kavana at the end of each brocho of the amida (Tur O.H. 101, Mishna Berura ibid.:1, see also Eretz Zvi 22 quoting Chinuch).
Horav Shlomo Miller’s Shlit’a opinion is that when someone has difficulty on staying focused throughout the whole shemone ezre, it is preferable to have kavana at the end of all brochos , than kavana during the complete brocho, of just a few.
Rabbi A. Bartfeld as revised by Horav Shlomo Miller Shlit’a