The higher a god's cultivation, the slower their progress became. Now that Ezequiel was the Lord of a Mid-World, the scale of time he operated within had expanded significantly.
At the moment, there wasn't much he could do. His Angels were too weak to conquer other Mid-Worlds, and capturing Low-Worlds offered no real advantage.
To resume his expansion, Ezequiel needed his Angels to reach the Nascent Soul Realm—a process that would take considerable time. An average, unnamed Angel required about 20 years to reach the Golden Core Realm, and another 250 years to break through to the Nascent Soul Realm. Named Angels, however, were a bit faster. Thanks to their True Name special ability, their comprehension speed was enhanced, allowing them to reach the Golden Core Realm in just 15 years and the Nascent Soul Realm in 200 years.