In response to your last Question - I calculated the probability for THE SAME number showing up on all 6 wheels when all of them were spinning 1 time concurrently.
And why is this any different from betting 1 number for 6 spins on the same wheel??
Aren't both of the cases independent events, therefore 2.7% accumulated probability, simultaneously or not??
The only difference exists only if we increase the amount of numbers we bet per spin, no matter if are on 1 wheel only or more than 1 wheels on the same time.
For example if I bet 35 numbers for 1 spin my probability is 35/37 or 84.6%, I could win only 1 unit and lose 35 units.
If I'd bet 1 number for 35 spins my overall probability would be approximately 64% to hit at least once, I could win as many times as my number hits multiplied by 36 and in the worst case I'd lose 35 units.
If what you said was true then no matter how many times I bet a single number, whether I'd bet it only once or 1 million times, the probability would always be 2.7%, of course this is far from truth!
Just consider that NEVER in the history of roulette have happened the following events:
1) a single number to be absent more than 666 consecutive spins
2) all 37 numbers appeared in 37 consecutive spins (regardless of their order)
3) a single number (any) appeared for 37 spins in a row (most has been recorded 7 spins)
Now ask yourself why, are those events reflecting the same 2.7% regardless of what happened?
There are extreme deviations but not everything
After the decades of roulette history, the gazillions of accumulated spins from casinos around the world, if such ''travesties'' events where possible then they must have already occurred at least once.
Random has its limits like everything else in universe.