6-pack is mostly genetics (after the clean eating and exercise components, of course). If you look at true six-pack owners, most of them are shorter folks, with shorter muscle bellies (at least among women). This look is very hard to achieve. The taller you are, the generally longer the muscle bellies, and the longer look you will have. Notice that Cathe and her team all have the 6-pack, and they are all under 5'6" (Rhonda - the tallest - doesn't have one). Then, look at for example, some of the female beach volleyball players - super-fit people (Gabby Reece and ? Walsh) they are quite tall, and have long, lean torsos - no six-pack. Some people are just not destined for that look, no matter how fit.