Is it obligatory to equalize the morning and evening repetitions of the recurring adhkar, such as repeating "Subhan Allah wa bihamdihi 100 times" three times in the evening if it was said three times in the morning?

It is not obligatory to repeat the morning dhikr (remembrances) with the exact same number and manner. One can limit it to one hundred or more, because the Sunnah remembrances are not established as obligatory except with proof. It is Sunnah to observe them regularly and to make up for any that are missed. Imam An-Nawawi said: "It is befitting for whoever has a regular dhikr... and misses it: to make it up." And it is reported in Sahih Muslim from the Prophet, peace and blessings be upon him: "Whoever sleeps past his hizb (portion of recitation) or part of it, and recites it between the Fajr prayer and the Dhuhr prayer, it will be recorded for him as if he had recited it during the night."