Hi,
Based on how Cathe puts them in the rotations she devises for us, either way works. Personally, if I have the time, I like to do the whole series in three consecutive days (Tues-Thurs, for example), then finish off the week with one total body workout, perhaps with an endurance focus (eg., Muscle Endurance on Saturday).
If you do one workout, do a second one the following day ONLY IF you are not feeling too sore from the the first one. If you are really sore, take a day between. Many of the moves incorporate muscles from the other body parts, so sometimes a day between would be warranted.
They are a great series. Enjoy!
Sandra