Is it necessary for the Night Vigil Prayer (Salat al-Qiyam) to be performed in congregation?

The Night Prayer (Qiyam) outside of Ramadan is performed individually, unless a man prays with his family members for encouragement and habituation. As for Ramadan, the prescribed way is to perform it in congregation, following the practice of the Prophet (peace be upon him) and 'Umar (may Allah be pleased with him) who gathered the people behind a single Imam.