Surely thats because 10+ in a row is only gonna happen so rarely in comparison.
Personally IMO this is where your going wrong, a good, disciplined roulette player isnt trying to win 10/15 spins in a row or even every spin, you can lose 200 spins on a session and still be up whether you have won only 50 spins or 201 spins in that session its all about the betting, which is the only real defense you have against the house edge.
Like all roulette players I have tried a zillion methods, some good, some bad, and some just plain ugly! But ( and im sure i will get shot down in flames here ) im a firm believer that roulette can be beaten on a honest game, due to having encountered people in the past that have proved it over many months and many thousands of spins.
However its not easy, its very much a game of patience if anything and unless your using a size able bankroll with strict play, your not gonna make your millions lol
Like all gambling it should really be just seen as entertainment with a chance to win a few £££