Ultimately, the frequency with which you work with a personal trainer depends on your schedule and your trainer’s availability, as well as how much of a financial commitment you are willing to make. In other words, if time and money are of no concern, you could perform all of your workouts with a personal trainer. Typically, people hire trainers to: (1) educate them about safe and effective exercise techniques, (2) provide them with an individualized exercise program, and (3) assist them with the motivation to stick with the program to ultimately reach their goals.
From a personal trainer’s perspective, it’s rewarding to help clients achieve their health and fitness goals through a successful exercise program. As a trainer myself, I can tell you that in my job nothing beats the feeling of seeing my clients accomplish what they set out to do as we work together to make it happen. When their goals are completed, however, I have an honest conversation with my clients about continuing the business relationship. On the one hand, if I’ve done my job correctly, I’ve taught my clients important lifestyle strategies and given them access to resources that they can use and develop further on their own. I don't want to create a situation where the client feels like he or she cannot exercise unless it is with me. Instead, I want to empower him or her to adopt regular physical activity as part of a lifestyle that includes daily movement. On the other hand, I have worked with some of my clients for years because they enjoy the rapport we have together and are interested in continually learning more about health and fitness. These clients push me to constantly seek out new research and information on exercise and wellness because they look to me as a trusted resource in this area.
There really is no “right” or “wrong” answer to your question of how often one should work with a personal trainer. Ultimately, the client needs to determine what he or she wants to accomplish by hiring a personal trainer (e.g., learn a whole-body exercise routine in three sessions, find new ways to strengthen the core to prevent back pain in one session, or get ongoing support for long-term health and fitness goals) and the time and financial resources available to pursue this goal. Once that is decided, it should be easier to determine how many sessions it will take to reach your goals and how frequently to meet with the trainer.