Most systems will fail,... and even the best system can lose sometimes. (Losses have to be accepted)
But to be realistic you can have a system that wins 8/10 times or 9/10 times
I have invented three such systems, still most people don't care.
Hi Ignatius,
Not often I post here, but you may know I Always read your posts. Especially targetting the 3 neighbours when a single number shows within X spins. I liked that, I won over 4000 with that. Unfortunatelly for my bankroll it was not a longtime runner
. I Always appreciate your posts 
, keep up the good work.