However, a class at least once a week is beneficial to 99% of our students. Normally, students benefit from more than one 60-minute class each week to work in-depth on their voice and watch a song at the same time. This gives the teacher, and you as a student, an idea of how well you are practicing and progressing. The standard frequency of classes is one class per week.
Some people want to do more right from the start and others want to do less than that. For most people, I recommend consistent weekly classes as optimal if possible for them. In my experience, people who plan to do two or more lessons a week find that they don't actually progress much faster. It takes time for the body to develop new habits, and singing is a rather sophisticated process for the body, since many things have to align.
Try to take a class at least once a week. If you can have more, you'll progress faster. If you can't, remember that practicing at home is just as important as the lessons themselves. The only way a good singer can stop thinking about his voice and start thinking about the songs he is singing is by training his usual vocal patterns to the point where healthy vocal technique is on autopilot.