Having multiple programs within the same catagory takes up a lot of space on a page if you have a seperate site. This would be the case if you had say 5-10 6 week programs under a certain catagory like "weight loss" or "Strength" workouts. Being able to use a single link to checkout on your site providing the choice of each program purchased individually or as a group in checkout would assist in making ones site look nice. This would also allow the potential client the choice of all the programs. This way they wouldn't have to go back to the page with the program link if they wanted to purchase more than one program.