How long can a 10 and under meet session last?

Except at championship and open water meets, age group meets must be planned so that events for swimmers 12 and under finish in 4 hours or less per session (Article 205.3.1F).

The same 12 and under swimmers are limited to one session per day. The exception is a prelims/finals meet, where they can swim one prelim session plus the related finals.

Development meets (for 12 and under swimmers, with shorter events such as 25s) have sessions of no more than 2 hours, and each athlete swims in only one session per meet (205.11).

Meets for any group should finish within 8 hours of competition a day, with meal and rest breaks (102.1).