Is it permissible to divide the remembrance of "Lā ilāha illā Allāh waḥdahu lā sharīka lahu, lahu al-mulku wa lahu al-ḥamdu, wa huwa ‘alā kulli shay’in qadīr" throughout the day, such as saying it 50 times after Fajr and 50 times after Asr, or 20 times after each obligatory prayer, in order to attain the reward mentioned in the Hadith, or must it be recited consecutively to obtain this reward?

The "Morning and Evening Adhkar" (remembrances of God) can be recited throughout their respective times, but it is better to say the adhkar that have specific numbers all at once to avoid error or forgetfulness and to gain early protection. Also, the numbers mentioned in the adhkar are divinely prescribed and should not be violated to ensure the reward. However, if one recites them separately, there is no sin upon them, and they will receive the same reward.