Meeting with your instructor once a week is the best way to learn guitar for most intermediate level students, as it allows for a steady growth of skills. If you need more time to master the new material, you can switch to classes once every two weeks until you feel more confident. Practicing on your own every two weeks should be enough. As you improve, you will want to guide yourself to your own sound.
Frequent classes won't help you move quickly if you don't practice between them. All students should work with their instructor to determine how often they should attend classes and create a personalized plan to achieve their guitar goals. Taking guitar lessons more often can help you progress faster. In the early 2000s, taking a guitar lesson meant that someone had to schedule a class with a local instructor and take the student to the lesson, wait for it to finish, then pick them up and take them home.
However, online guitar lessons are much more affordable and accessible. I recommend that a child start playing guitar at age seven, but be careful to limit the frequency of required lessons. The cost of in-person guitar lessons will also have a significant impact on how often you can or should take them. In optimal situations with fast Internet, low or no latency, and clean video and audio, these online systems would be almost as effective as in-person guitar lessons.
There are also many other resources besides traditional lessons that influence how you can learn the guitar. For almost all musicians, having a consistent guitar lesson schedule is essential, especially in the beginning stages. The online option might be better for children who are shy or who don't like the idea of interacting with a guitar teacher. Deciding how often to take your classes is one of the many decisions you'll face on your guitar journey.
My recommendation would be to choose the Justin Guitar Beginner course, it is a structured form of learning in which many bases are covered and you get an excellent base for playing the guitar. As a general rule, in-person or tutoring classes will average once a week, while online guitar lessons (perhaps in much shorter periods of time) will average once every two days.