Floating needs and wants will vary greatly from person to person. Generally speaking float sessions are 60 minutes and 90 minutes.
We have seen float sessions last many hours, including ALL night, even!
But do not feel bad if you "tap out" just 20 to 30 minutes into the first session. Letting go is hard to do. It is a process to teach the body and brain to relax, to let go and just be fully present without distractions. Some need to increase their time each visit working their way up to 60 or 90 minutes or longer.