In the name of Allah, The Most Gracious, The Most Merciful
I do not know any basis about this division either from the sunnah or from the actions of the companions (may Allah be pleased with them), may it was done to make it easy on people when their determination became weak or what may be considered a proof for this is what was mentioned by the Hambalite jurists who stated that it was detestable to perform an optional prayer during a break in the Taraweh prayer. He said, "What is this prayer?" Do you pray while your Imam is in front of you still leading another prayer? Whoever goes against us is not from us." Another example mentioned by the jurists is performing an optional prayer after a Witr prayer which is performed in congregation regardless of whether the interval is long or short.
Before that, the some Shafites jurists mentioned that it was called Taraweh because they rested after performing prayer and made complete tawaf between two Taraweh prayers. This was mentioned in Hashiati Qalibu and Al-Qasimi mentioned it in Akhbar Makkah (2/155).
And Allah knows best.
Your brother,
Dr. Khalid al-Muslih
17 / 09 / 1424 AH