Martingale only works for very short term and if you have luck ,you will lose faster if you play at site which have bigger house edge
Short term or long term it doesnt matter because martingale mean to fail in the first place. I have never seen anyone who got profit by using this strategy. Many top player in Primedice or bitdice for example never use 2x payout and double on loss, they change it to another variance like 66 % to win