The bets to look for are the "corner numbers" of dozen 2 & 3:
Doz 2 "corner numbers": 13,15,22,24.
Doz 3 "corner numbers": 25,27,34,36.
Trigger: Wait until either Doz 2-corner numbers hit OR Doz 3-corner numbers hit. When this event occurs, bet those corner-numbers not hit.
For an example, if one of Doz 2-corner numbers (13,15,22,24) hit; Then you bet the Doz 3-corner numbers: 25,27,34,36. With 4 numbers progression, (until hit).
Likewise, if one of the Doz 3-corner numbers (25,27,34,36) hit; Then you bet the Doz 2-corner numbers: 13,15,22,24. With 4 numbers progression, (until hit).
4 numbers progression 1 1 1 1 1 1 1 1 2 2 2 2 3 3 3 4 4 5 6 7 8 9 10 12 14 16 18 20 23 27 30 35 40 46 52 59 68 78 89 101 116 132 151
I played this and was +259u, before I stopped.