I don't think there is any myth behind when to gamble and when not to. All this are just normal fallacies that we'll had been told when we were Young. A lots of drama had been attached to playing bets because of loses that gamblers are trying hard to avoid. Just gamble and enjoy yourself if you eventually make profits. If luck will come to a person when gambling, I think it will come anything will speculating the time.
Also have the same opinion regarding to myths behind times since actually we do have different time to play since majority of the gamblers have busy schedule and most provably majority play at their free time to relax and be entertained for quite short time. We can blame other believe for myths or other rituals since actually other spread something like that and create false opinion that it works that's why some newbies believe and hoping it will work to them so that they can earn money.