Q. If someone after thirty days of saying Mashiv Haruach and even after repeating it 90 times, still catches himself as forgetting during the brocho. If he indeed was totally unaware if he said it or not, can he rely on the chazaka of thirty days?
A. Horav Shlomo Miller’s Shlit’a opinion is that if one finished shemonessrei and cannot remember if he said Mashiv Haruach or not, after thirty days of saying it or after having repeat it 90 times, he can assume it was said. Even if he still catches himself occasionally forgetting it while reciting the second brocho.
See also question 658.
Rabbi A. Bartfeld as revised by Horav Shlomo Miller Shlit’a