Everyone has different levels of mastery regarding the type of gambling they are interested in, and gambling on matches that we really don't know about the performance, team and also the latest information, of course makes the risk double... it's better if we only gamble in areas that we understand, and on teams that we understand... the more we understand the condition of the club, the greater our chances of winning the bet...
The point is not how many sports we should bet on, but how many clubs or teams we understand in the game, unless you really rely on luck alone, you can gamble on teams that are even foreign to your knowledge.