Something ive experimented with for fun... 19 number bet (see pic!)
but only the 7 numbers within the middle column matters here.
i calculate 5 losses, (if 2 corners hit, that i dont calculate as loss. if any of the single corners hit, i calculate that as loss).. ok
so, progression (both positive and negative)... After 5 losses i double up. When hit i double up. (sometimes i do not double up after 1 hit.. Until Reached a new high, then i reset...
Also, after 2-3 hits, i use to switch the bet, between the High and the Low side...
Thats it.
Seems to work OK
Use your own progression and moneymanagement if you dont like mine, (also i havent tried Flatbet)...