For some, even one set for certain body parts may prove more than the individual can tolerate or even need. For instance, over the years, I have had training clients, who informed me at the start that they couldn't stimulate growth in their calves, whether they were training them with 12 sets three times a week or just one set once a week. They took my advice, acknowledging the possibility that even one set may be too much, then ceased training their calves entirely. These individuals reported to me on a regular basis, claiming calf increases of 3/4" to 1 1/2" in several months.
Similarly, I've had clients who gained quite well overall with their greatest circumference increase in the neck. These examples prove the reality of "indirect effect", i.e., when growth is stimulated in one muscle, growth is stimulated through the entire musculature - though to a lesser degree; and the larger the muscle being worked, the greater the degree of indirect effect.
The calf increases reported above were likely the result of the effect provided by Leg Presses, Squats and Deadlifts; with those experiencing tremendous increases in their neck being the indirect result of growth stimulation induced by Shrugs and Deadlifts.
Conclusion: If you have a lagging body part, stop training that part entirely for a few weeks, then resume training with a lesser number of sets, or, with calves and neck, stop training them entirely.
Mike Mentzer