If you only have a 10% strike rate, then you will need most of your winners to be more than 7-1 then, wont you.

The law of the third indicates that a 37 numbered wheel will have hits on 2/3's of the numbers if spun 37 times.
So one third will not hit.
That is the theory.
I will look out for the fellow again, and report on how he does next time.