I challange any one to try to come up with a march that win more then my solution - it is Amazing how effective it is.
Here is two solutions following the random path with 1 in 3 probability.
The first march:
You see dozen 1 you play dozen 1.
You have dozen 1 and 2 you play dozen 1 and 2.
You always follow the last hitting dozen and play against dozen to alternate 123.
Lets say you see dozen 1 then you play dozen 2 and 3
Lets say you see dozen 2 then you play dozen 1 and 3
Lets say you see dozen 3 then you play dozen 1 and 2
Until two two loses, then you wait for a fictive win and start over.
I test the second march flat betting: