A couple tips for students: - If you want to have informal conversation lessons, booking a lesson as short as 30 minutes once or twice a week can be very helpful, since that timing allows for a lot of interesting topics to arise. These lessons are usually the cheapest lessons too. If your level is more intermediate or advanced, longer lessons will be even more helpful, but fluency needs to be built little by little. - If what you want to learn is grammar, prepare exams or you are starting to learn a language from the very start, it will be most productive for you to book lessons that are 45 minutes minimum and an hour and a half maximum. These lessons require longer explanations on behalf of the teachers and it takes more time to explain everything to students and help them achieve their goals.