I like betting on 6 numbers, so I win about 1 in 6 spins.
Its comfortable amount to martingale two times on 7th and 13th.
4 numbers seems like droughts can be too brutal, 8 numbers and the payoff seems too small.
6 for me Is just enough on the wins, like when it hits 3 or 4 times before the "7th" spin to make my losing trips not feel so bad