Doing them on different days does not emphasize muscles more. For example doing flyes on day 1, bench on day 2, and cable crossovers on day 3 isn't going to make your chest any bigger than doing them all one one day.
Legs have huge muscles that require long recovery times of 6 days or more. If anything you maybe could split up quads vs. hammies but personally I do them all on the same day.
JC