Peaking isn't a magic track and you're not going to jump into this unreal shape out of nowhere without previously doing the work. I'd say it
Is a combination of a few things, those being: freshening up, increased speed, late season fitness, not overtraining.
After months of handling a full workload, if a coach has trained his athlete properly, then he should experience his fastest times at the end of the season. This is obviously because more time spent training should equal better fitness. However, if you push too much too quickly than you will "burn out" or have your best times before you want to (like going prematurely). So peaking is avoiding this phenomenon combined with backing off mileage (both in a week and the volume of a workout)slightly as well as adding in a bit more speed work so that the athlete is feeling light on their feet and fast come race day.
So yes peaking exists if you have ever seen an athlete finish off a season with his best race. But there is a lot more to the process than doing the right workout in one week--the whole season is geared towards it. The key is patience.