This is a nice and heated idea, everyones work flows vary and often for the first few years of animating it changes a little bit every shot. I know for me it has, I did some straight ahead spline, some spline blocking hybrid, a strange combination of everything that ended in mush before I ended up with something that resembles the way I work now.
In this post by Animation Addicts we get a little insight into the idea of blocking and the different ways one can go about doing it as well as some pros and cons of each variation.
Right now in most my shots I do a general blocking pass with sketches to sell my key poses and after talking it over with some friends. I test it in Maya in stepped mode. After feedback I'll tighten that up into 2's or 4's, sometimes 8's depending on how much movement is in that section and make sure everything is working. In this time I might switch a few controls into spline to test the pace but I always make sure to keep my keys in columns. Once everything flows then that is when blocking ends for me and I can leave stepped mode with all the controls.
When does blocking end for you? What's your favorite way to block out your shots?