House edge vs numbers bet per spin

[Rajb]

Help any maths heads!
Hi
I have a question- what is the average number of numbers covered (bet) per spin vs winning spins to beat the house edge .
Is there a ration of how often you would need to hit a number per x spins with x numbers covered per spin?
I see systems that seem reasonable snd claim to beat the 2.5 edge. But how would you know how many numbers you can cover per spin ( or should cover) ...
Thanks anyone
Thanks