Something that happens once in a million spins is a once in a lifetime event you may never see. But if you can find a way to beat this worse case scenerio, then you have a Holy Grail.
Based on a million spin test results, it seems like they all have something in common. If you multiply the odds of hitting by 12, this is close to the worse you'll ever see. Random does have limits.
For example, take an even bet (red/black, odd/even). The odds are 1 to 2....2x12=24. 24 misses will be the worse case.
For dozens the odds are 1 in 3. 3x12=36. 36 misses before a hit will happen only once in a million spins.
A four number bet, or quad, has a 1 in 9 chance of hitting. But the worse case scenerio for a quad to go missing will be around 108 (9×12).
Not sure if this will be of any help to anyone. I did find it interesting that most worse case situations over millions of spins all were very close multipliers of 12.