Open studio isn't for beginners or even people trying to 'get back into it' after a long hiatus. Open studio should be for practice and perfecting, not teacher led but teacher floats from student to student as needed. Structured class is for learning the basics, new skills, teacher led and directed. There is also lab time which is for practicing the basics where often the teacher is not present, and directed study which is project based with a goal in mind that teacher and student touch base often to help the student achieve the goal.
I have done private lessons but only with those that have taken classes before or have more experience. They actually have been more like mini-directed studies, like can you come over and help me figure out how to make this(and there is a specific form they want to explore).