Are self-adjusting brakes really self-adjusting?

I found Eastern Marine several years ago when I needed brakes for our boat trailer. I've since seen that they have a lot of RV parts. In RV, they're strongest in Brakes and Lights. They run some pretty good sales and specials. Particularly at those prices, it really does make sense to Out with Old and In with New. They also have some sales people who know something about their products.