How could the Messenger (peace be upon him) repent more than one hundred times, and what are the best times for repentance?

Ahmad, Abu Dawud, and Al-Tirmidhi narrated from Ibn Umar (may Allah be pleased with them both) that they counted for the Prophet (peace be upon him) in a single sitting one hundred times [the supplication]: "My Lord, forgive me and accept my repentance, for indeed You are the Acceptor of Repentance, the Most Merciful." Thus, what is recommended is to increase in seeking forgiveness at all times and in all circumstances, especially at the time of pre-dawn (sahar) and after prayers, and to seek out times when supplications are answered.