Winning and losing streaks are all simply statistics and probability.
For a near 50:50 bet like ATS sports or Red Black roulette, for example, the top end on the longest winning or losing streak is 19 - 20 in a row. It would be easier on the bankroll if they were more evenly distributed but it is a fact that you will sometimes have wins or losses bunched together like this in long streaks. It is nothing that you are doing as a bettor, just probability. In the long run you are close to 50:50, but in the short run you may streak.
Of course, if you significantly increase the long term win rate to 60%, 70%, whatever, your maximum winning streak will be longer and your maximum losing streak will be shorter, completely due to the higher win percentage that you acheive.