Conceptually, to pray 2 rak’ah tahajjud on a daily basis is better than to pray 10 rak’ah once a week. This is based on the well-known hadith that ‘the most beloved deeds to Allah are those done continuously, even if little’ (Bukhari).
The reason is because these continuous deeds are an evidence of your *commitment* to pleasing Allah. The deed isn’t the be-all and end-all, it’s how much discipline you have to put Allah first, regularly.
Interestingly this is in all aspects of life – in good and bad deeds. Discipline is needed to establish the 5 daily prayers, to recite your wird of qur’an, or to distribute food weekly at the local food bank. Or in the cases of evil deeds, to stop the Nafs (soul) from succumbing to it’s desires.
In all cases, it’s the small, daily battles of good vs permissible vs evil which either raise or debase an individual.