Supernovae eject their processed material at very high velocities. The collision heats the material of the interstellar medium, though. Gas gets mixed together by repeated supernova shocks. But for stars to form, gas needs to cool down and collect into dense clouds. Takes a few million years to cool down to become a molecular cloud .
Stars form from cloud, cycle repeats, galaxy gets more enriched.
Even stars like the Sun have winds but very low-level ones. For low-mass stars, about half of their mass will be returned to the ISM by the time they become a white dwarf. High-mass stars return much more. Not only more mass to begin with, but they also return a larger percentage of their mass. During the supernova, nearly all their mass is lost during the explosion.