At first, for a while it may be a good idea to do just one class a week if you are not very used to physical activity, but soon they should become two, which is the ideal frequency for a beginner-intermediate level to gain technique and strength quickly but without too much effort if you are not an athlete. As a new pole dancer, for your first 3 months, you should try to practice or attend a class once a week. While there's no real way around it, this lack of strength in the early stages of learning polo can cause movement compensations that can build up for years before they start to cause problems. As an instructor, it can be difficult to do a full workout during a pole dance class you're teaching.
As dance, exercise and art in which grace and required skill come together, it takes hours and hours of practice to improve pole dancing. If you are already physically active, you should also consider your other workouts besides practicing pole dancing, being careful not to overdo it. Some of the fastest and best body transformations in pole dancing occur with a good quality training program. Since you're now an advanced-level pole dancer, you should try to make your warm-ups and pole conditioning more challenging.
If you're preparing for a pole competition or a performance, you'll have to follow a very strict schedule to stay on track. In fact, it's easy to underestimate the force needed even for beginner movements, such as spinning a chair or climbing with a pole. Considering that pole dancing is a very intense form of exercise that exercises your muscles in ways that you probably haven't done before, it's common to be careful when it comes to overworking. This will largely depend on the level you are currently at; the pole dance training schedule may vary for the novice or the beginner, the average or intermediate and the advanced.
Many advanced students attend 3 classes per week, but if you can't afford it, there's no better time to invest in your own polo. For example, an inverted shoulder frame or a Superman were considered advanced movements for learning pole dancing. You should definitely consider another form of strength based exercise, to complement your pole dancing training. As for how often you should practice when you're at an intermediate level, you can surely practice at least twice a week, with at least one free training session, if you're really trying to improve your pole game.