The most important reason of my submissions to these calls is the feedback I'll have on my work. I did the same on B&W Awards last year, and the repport I received was very usefull to me, in order to improve my way as an amateur photographer.
I really like street photography, where you can get natural, unusual, and lovely images.
Of course, you have to pay attention on what happens all around you, and be fast enough not to loose a great moment.
Sometimes you loose, sometimes you succeed.