The answer to your question can come in many forms but my first response would be “a lot always depends on the type of workouts you’re doing.” Sometimes people, including trainers, look for complicated answers and solutions when in fact it ‘could be’ something basic. If the workouts are not targeted towards reduction in body fat, then someone could literally exercise EVERY day (I’m not condoning that 🙂 and still show little or no results. As ‘they’ say, the devil is in the details, so it’s not really possible to give you a definitive answer without knowing a whole lot of details (types of workouts being one of the main ones).
I train and teach by example, so here’s one. Let’s assume someone wanted to improve their cardio so that they can fun a marathon. They go to the gym 5 times a week and lift weights. Two months later they wonder why they still can’t run far without getting exhausted? The answer of course would be because they weren’t training correctly for that goal. The same ‘could be’ at issue here. Just something to consider.
I hope that this helps.