A single float can be valuable, but it is also your first encounter with a completely different environment. A short practice helps you separate the novelty from the experience itself.
Float one: meet the experience
Learn the room, the pod and how your body responds. Curiosity and adjustment are a normal part of the first session.
Float two: let go sooner
The practical details are familiar, so more of the session can be spent settling rather than working out what happens next.
Float three: find your rhythm
A third session gives you a more useful basis for deciding how floating supports rest, recovery or mental space in your own life.