Mike, assuming that you’re using relatively small incriments, you’re still using more than enough weight each workout to stimulate a muscle.
For example, generally speaking most people seem to be using 5 pounds increases per workout for their upper body, and about 10 for lower. So, if you predetermine your max at 100 lbs, and it takes you six training sessions to reach that max, adding 5 lbs each time, then your first workout, which is the easiest in terms of weight...would still have you lifting roughly 70% of your max.
Of course, for the purposes of my argument, using a nice round number like 100 makes things easier, but my point is that the weight increases are usually kept small enough so that, even starting out, you're close enough to your 15, 12, 10, 8, or 5 rep max to cause microtrauma each workout.
You will have to fool with the weights a little to determine how your body will best respond, especially with small muscles. For example, I have to use 1.25 lb increases for side or front raises, or I would be starting with 0 and ending with 30. Good luck with the program, and read the previous HST threads, both here, at thinkmuscle and the HST site. Hope this helps.