As the marked lambs began to appear, Jakob did not mix them back in. Targum Pseudo-Jonathan is precise: he set them apart, placed them in front of the remaining flocks, and then quietly gathered every various-colored and every black animal he could lawfully claim (Genesis 30:40).
He kept Laban's sheep separate from his own. Not a single one of his growing herd was allowed to blur back into the household of the man who had tried to cheat him into dust. Boundary was his protection.
The detail matters because it shows us a Jakob who had learned from fourteen years of exploitation. He was no longer a young man who trusted whatever arrangement he was handed. He was a shepherd who drew his own fences now, and who refused to let the line between what was his and what was Laban's become conveniently unclear.
The Maggid teaches: righteousness sometimes looks like separation. Not out of hatred, but out of clarity. A man whose fortune grows beside a cheater must keep the flocks apart, or he will wake one morning to find he cannot tell which animals were ever his.