Fumbling 145 days long kindle reading streak
If my memory serves right, Snapchat popularised the streak phenomena. Later on, the amount popularity and stickiness it creates among the user, many companies jumped on the band wagon - fitness trackers, calories trackers and many more. What the streak does is it creates a habit among the users and make them to use the particular service on daily basis. Also, it creates a sense of pride with the longer streak on has.