I believe this dynamic is exactly what MRVs were designed for. One missile with numerous war heads, arriving on target one after another in rapid succession (independent targeting came later.)

There are some videos of MIRV reentries on youtube that really something to see. Seeing those bright lights come down from the sky in a line, one after another, is simultaneously chilling and awe inspiring: https://www.youtube.com/watch?v=j7X89a531CY