Often when I work out abs I mix them in throughout a whole workout. I will do maybee 2 sets of bench then a set of weighted inclince crunches, finish bench then more crunches...a few sets later more crunces and eventually twisting crunches too. As such I end up doing maybee 6 ab sets over the course of an hour (I do this maybee twice a week). I like this as it helps me break my workout up a little and saves some time. Is this ok? or should I be doing my ab sets all at once as their own exercise?