Test with this sim freehttps://gamble-galaxy.com/ytube/systems/3evens/index.html
Not for sale its free, You bet the opposite to every 1/1 bet from the last spin, so if 7 lands you bet even/high/black, treat the bets as separate bets with progressions, so if any don't come in the progress as you would with marty or fib etc etc, if one comes in and 2 don't then keep betting the opposite.
The sim will make it easier for you to understand.