The next thing to look at, what are the goals of the client? Many clients like personal trainers simply to help them work out, no specific goals but general overall fitness. For these clients, percentages are probably unnecessary as you as the trainer can monitor their intensity and effort by watching. If it is an athlete preparing for their sports, intensities will give you a great guideline to go by and allow you to accurately pick a weight for their work sets that will increase their potential for strength.
This will help you in several ways. First, it is easy to look down the list of affiliates and think of new ways of working on marketing them. Maybe you will want to put two or three of them together and market them all on one page. Then tell your customers that if they join all three you will throw in a fourth package that you have resell rights for. Second, you can easily either click on a link or cut and paste an address into your web browser to see how you are doing. And you have your username and password right there to cut and paste as well. Percentages in personal training can be absolutely invaluable. However, they need to be incorporated correctly in order to get the benefit out of them. One thing to think about, are percentages necessary for your clients?