One of the benefits of playing bridge at clubs and in
competitions is that most sessions are usually three hours
or slightly longer. The main benefit to the young player is
that they learn to alternate heavy concentration with short
spells of relaxation. It has been noted that they find exams
easier.
This applies to younger children too. We had nine and ten
year olds playing against adults often with an adult partner
on afternoons during school holidays. One session two nine
year old boys playing together won against the adults.