When you are first learning to meditate, we recommend you start slowly with a ten-minute session.
You can adjust the duration of a session by clicking the down arrow next to the time on the mobile app, or clicking the blue clock icon next to the duration after the session launches from the desktop version.
Just like with physical exercise, it's best to slowly build up duration. Of course it's fine to continue with more than 10 minutes a day. The body and mind will adapt very quickly.
Science has shown that 10 minutes on a regular basis delivers proven benefits.
If you have both the time and the inclination to practice for a little longer, that can be a very positive thing. Most people feel challenged at first, but then after a few days of adjusting, they can't imagine sitting for less.
One thing that changes as you sit longer is the degree of clarity you experience. It takes a little time for the mind to settle down and only then do we see its contents clearly. This process can feel a bit like a magnifying glass or microscope slowly coming into focus.
At the end of the day, quality is more important than quantity. Even practicing one minute of awareness is valuable. Pick a duration that works for you and build a regular practice. Without putting any pressure on yourself, increase the time when you're ready.