When we change to saying "mashiv haru'ach" one is required to recite the shmoneh esrei again if he is unsure if he made the insertion. This site points out that one becomes habituated after 30 days (or 90 repetitions). This site makes the halacha explicit:
The Mishna Berura (ad loc.) explains that one says.... Rav lehoshia Mashiv Haruach U’morid Hageshem, 90 times. He quotes the Chasam Sofer (Responsa Vol. I 9:20) as well, who opines that one repeats it 101 times, but only if one has said it less than 90 times would he repeat the Shemoneh Esreh.
Therefore, the practice is for someone to go home and repeat the phrase until he passes the threshold of repetitions so he no longer has to repeat the davening.
While we only make this change for 10 days, we replace "ha'E-l hakadosh" with "hamelech hakadosh" and require one who does not say the proper version to repeat the davening.
Can one go home and say "hamelech hakadosh" 90 (or 101) times on Rosh Hashana so that if he is unsure during the aseret yemei tshuva whether or not he made the switch, he can assume he did?