My own rule is, when I play, that if I see 3 numbers in one dozen, I avoid betting, and wait for number appearing in another dozen. When it happens, I spin one more time, because I often see that after xxx (example 2,10,6) a number appers in dozen 1,1, then came up 31 (no hit example on the target dozen), then we have 6,1,31, target dozen 2 and 3, but came up 2-3 numbers in dozen 1, so after 3 numbers in one dozen( in our example it is dozen 1) I avoid betting and I wait for number sappearing in another dozen. If it happens I spin again to appear number in dozen 2 or 3, avoid losing. Hope it is clear.