Once the plagues hit Egypt ― blood, lice, frogs, etc.
― the devastation continues for over a year (Talmud - Ediyos ).
If He wanted, God, an all-powerful being that He is, could have made all the Egyptians drop dead on the first encounter with Moses, or He could have frozen them in place, then all the Jews could have packed up and left in five minutes.
To explain why the Ten Plagues had to be, we need to first explain the Jewish view of miracles in general.
The oldest known copy of the epic tradition concerning Atrahasis can be dated by colophon (scribal identification) to the reign of Hammurabi’s great-grandson, Ammi-Saduqa (1646–1626 BC), but various Old Babylonian fragments exist; it continued to be copied into the first millennium BC. These new texts greatly increased knowledge of the epic and were the basis for Lambert and Millard’s first English translation of the Atrahasis epic in something approaching entirety.The obvious question we must ask when we examine The Plagues is why?Why did God choose to set the Jewish people free through this very long, drawn-out process ― an entire year? He knows that only certain impurities are released at certain temperatures. The more dross removed, the less distorted his image. To gauge his progress, the refiner looks for his own reflection on the surface of the melted silver or gold in the crucible. The Atrahasis story also exists in a later fragmentary Assyrian version, having been first rediscovered in the library of Ashurbanipal, but, because of the fragmentary condition of the tablets and ambiguous words, translations had been uncertain. traces the model drawn from Atrahasis to a corresponding passage, the division by lots of the air, underworld and sea among Zeus, Hades and Poseidon in the Iliad, in which “a resetting through which the foreign framework still shows”.