Martingale method may work for few people that are lucky enough to recover the losses but for most people it will never work. Rather it will just going to make the losses become even more bigger. I will never ever recommend this to some for people who are worried about the losses they have made when they are planning to chase for it and try to take it back. I simply suggest to cool down call it a day and get to gambling on the other day or on the next day. It is hard to see people getting broke because of this common mistake.
As for long term approach on games that has a house edge, martingale strategy will never work.
Remember the words here " long term", that's because the odds are against us. However, if you do this on game that are based on skills, this might work for you, with a proper discipline, you might end up winning in the long run. Gambling site usually have their max bet limit, so that's the problem, you can't use it fully as the meaning of martingale is double every time you lose, what if you have 10 losing streak? Of course you'll need to bet bigger and that would possibly result to limit, so you just need to adjust a bit, maybe call it semi-martingale.