If I understand correctly, is this parameter configurable and the owner of the slot machine can significantly increase it? I remember how in my country (in wild times) crazy "businessmen" set up a slot machine in such a way that they had a 25-50 percent advantage 
And I had a friend who was doing this in the technical part, so we cannot know exactly what advantage the slot machine has.
Exactly most especially if the system is not a provably fair system verifiable one will be left in the dark the real advantage of the machine 🎰 and just keep losing to the House unknowingly. I wish we have a way to test the probability of a house configuration before playing on their machine. And I had a friend who was doing this in the technical part, so we cannot know exactly what advantage the slot machine has.In my example, I was talking about physical slot machines, there is definitely no provably fair system and you can only hope for the honesty of their owner. As for playing online, most of the casinos use this system, although I am sure that the house edge does not exceed 0.5-1 percent even where this system does not exist. It's just that for an online game, this indicator is actually the standard at which everyone is happy - both the player and the casino.