Pinball is random. the older video games have a pattern to most of the ones I have played. Once you learn the pattern the game is boring. Or it takes you forever to get to the levels where the game is challenging to you.
I can have a great game on most of my machines, hit start again & suck. But like someone else said, the skills transfer over from game to game.
That's also why certain repetitive pinball games don't get love. If it's just hit this ramp, or X shot over & over, that game usually won't last in a collection..