Sam2,
All punctuated equilibrium suggests is that instead of the gradualist approach that species are always in flux; most species tend to stay stable until subjected to various pressures at which point they start evolving at a “fast” (hundreds of thousands of years plus as opposed to tens of millions plus). It is not as radically different from the classical Darwinian approach as people seem to think and is not nearly universally accepted in either case and plenty of scientists say there is no need for it.