Well, speaking as someone who has been working in the industry and understands how outcomes work, I can't say that prayers work. In online casinos, there's the Random Number Generator. Its only function is to give random outcomes. One may pray for a 26 on online roulette or I don't know, for a winning or bonus round on slots. The chances for it to happen with or without prayers are the same. Random Number Generators are machines that don't care about anything else and aren't influenced by anything else (unless rigged, but that's another story and very unlikely at reputable casinos).
Even as a religious person, I also don't mix gambling and praying. I've always believed that praying is for special occasions and 'big' things like good health, surviving through especially hard times, etc. Sure, even in my career I'd find myself hoping that I'll be especially lucky and successful. But I generally believe that most things in life depend on my actions as a person and I wouldn't want to bother God with trivial things.
Whenever I win or succeed in anything tho, I always say 'Thank you God' even though I didn't even pray for that specific thing and worked really hard to achieve it.
