The procrastinator’s nature
There are no results on Google for “LeechBlock saved my life”, but there are testimonials like “Leech block has changed my life”, “Leechblock just saved my life”, and “This application is saving my thesis, and improving my social life”.
If LeechBlock isn’t working for you, you can try more extreme solutions like (on Mac) Freedom and SelfControl. (Found via this post.) But for me, right now, with my current level of work and self-awareness and other devices being employed, LeechBlock seems to be just about sufficient. (Although I do wish Safari were an even worse browser than it is.)