It is the most comfortable way for a student Because it's easier and cheaper than other ways to learn.
You can learn comfortably at your place or any place you choose. The schedules and the needs are chosen according to your availability and interests to improve.
Because they're made only for you You are just sitting opposite your teacher and at the same time you are improving and developing different communicative skills such as speaking and listening.
Because you have the opportunity to learn with a Spanish native teacher for 60 minutes. Nowadays in this busy life, it's really difficult to find someone who is able to help you improve an other language and with this way you will be learning with a teacher and with no rush. Just focus on your improvement.