This system takes advantage of the fact that colors repeat very often in a dozen.
Trigger: Wait for a color switch in a dozen. Now bet all numbers of the same color within the same dozen hit (all except the last number hit: 5 numbers bet) for 7 spins, then STOP and look for a new trigger. If the color switch again (in the same dozen within 7 spins), change bets to the new color and +1u bet. if a trigger is lost (after 7 spins) wait for a new color-switch trigger and +1u bet.
Progression +1/-1: +1u after 7 spins (for the next trigger) -1u if win for the next trigger. Reset when reach a new high.
First test was played with 5u bets,