They can not work in the sense of get over the house advantages. That's do not mean they are not useful. I can agree with some are voodoo. The same goes for other methods, like statistic, there is very little useful information when it comes to know which to bet (know about it is useful). Even claims from AP iare often just they had luck an evening using the ap-methods, and unlucky days blames the wheel ("as some are easier and other"). It is a game of chance, without cheating we can never sure win. The random in the game can make some players win and even win for long and much.
It is clever designed 1.3 to 2.7% HA, makes enough winners, so the casinos can stay in business.
The reason I play on line is I can get near zero house advantages and many chips for an Euro. I use methods, the reason is I can estimate which should happen for winning and losing, they do not predict.
There is some skill in the game, but not as know which number is next or some a head.