According to Art Devany, it does make a difference. These are excerpts from his Evolutionary Fitness Essay.
Most modern fitness prescriptions are static and agricultural. These programs model the body as a machine, not as an adaptive organism. Consequently, they prescribe a regime in which the body is underfed and over-trained. They are not based on adaptation, but on steady state analysis. These models assume the body is a linear process that maintains a steady state. In fact, all bodily processes are highly non-linear and these non-linearities must be exploited in any effective fitness program. The key to exploiting the highly non-linear and dynamic adaptive metabolic
processes of the human body is to achieve the right mixture of intensity and variety of activities.If your personal trainer is working you out three days a week, doing three sets of the same exercises, or, worse, 5 or even 6 days a week, find another trainer. You are flooding your body with hormones that consume lean body mass. These hormones also preferentially consume fast twitch muscle, the very substance you are after for strength, lean mass, and vitality. You are draining your adaptive capacity so that you cannot build, or even keep up with the load. Worse still, you are compromising your immune system.