The majority of the major leagues in the South are 10 sides per league, so 18 games. Starting 1st or 2nd weekend in May and finishing in the first week of September.
Sunday Cups or Mid Week T20s are additional, depending on how far you get; you do notice that some players minds shift from Saturday cricket to Sunday cricket, but these competitions do allow squad players an opportunity.
The more teams you have in a league, then you are then playing league games in mid-April and mid-September, when the weather is just more unpredictable or not "cricket weather". But do fully appreciate that people grow up on their surroundings and to some people they will quite happily play at these times of year.
Personally 18 is enough for me, with a few T20s midweek throughout the season.