There is no explicit text from Nabi (shallallahu alaihi wa sallam) specifying a minimum waiting period between two Umrahs. Scholars have differed on this matter. Some scholars hold that there is no waiting period — a person may finish one Umrah, exit to Tan'eem, enter a new ihram, and perform another Umrah immediately. Others recommend waiting until the hair grows back sufficiently to be cut again, as cutting the hair is one of the rites of Umrah.
Sheikh Ibn Baz stated that there is no prescribed minimum time between two Umrahs. A person may perform Umrah on behalf of different deceased relatives in succession during the same trip. He considered each Umrah to be an independent act of worship with its own reward. However, he noted that spending time in other forms of worship — such as Tawaf, shalat, and Al-Quran recitation — may be more beneficial than rushing between repeated Umrahs.
Sheikh Al-Albani held a different view, stating that repeating Umrahs in quick succession during the same trip has no basis in the Sunnah. He noted that Nabi performed only four Umrahs in his entire life, each during a separate journey, and never performed multiple Umrahs in one trip. He sunnah following Nabi's example by focusing on worship within the Haram rather than exiting repeatedly for additional Umrahs.