Haji is wajib once. Repeat Haji is boleh but contemporary scholars debate its advisability when millions await their first opportunity.
Haji is wajib once in a lifetime. Additional Haji is voluntary (nafl) and carries significant reward. Nabi was asked about performing Haji every year and indicated it is meritorious but not required.
However, with millions waiting for their first Haji, many scholars argue repeat jamaah haji should give way to first-timers. Arab Saudi now officially prioritizes first-time applicants, and some countries restrict repeat applications within five years.
A balanced approach: if your repeat Haji does not deprive another Muslim of their first opportunity and your finances allow it, voluntary Haji is blessed. But yielding your slot to a first-timer may carry even greater reward.
Source: Ibn Qudamah, Al-Mughni; International Islamic Fiqh Academy