Well I didn't always! When I first started learning CG animation I was coming from a 2D back ground. I never worked professionally mind you, but that's what I studied at University. In 2D, i worked Pose to Pose, drawing the strongest possible key poses and working between them. It just made sense!
Naturally, when i switched to CG, the stepped blocking method was the obvious choice. Like 2D, you block your key poses in, making them as strong as possible and work between the poses, breaking them down and forcing the computer into submission. Because on playback the interpolation between keys is stepped, you only see your key poses and modifying timing and adding breakdowns without seeing all the weird computer inbetweens really teaches you to NOT let the computer do as much as possible.
Because i didn't understand the Graph Editor, I avoided using it at all costs. To the point i was breaking shots down on 1s in many cases. This often gave me really nice blocking and blocking+ passes, but once i got into polish my Graph Editor was such a mess it was a nightmare to navigate. Things would be popping all over the place and the only way i could fix it was doing my own inbetweens.... ON EVERY FRAME. Now, there's nothing wrong with this approach mind you, it's just... kinda stupid.
Somewhere around halfway through Animation Mentor i was explaining all this and how i just couldn't understand the Graph Editor and my Mentor at the time suggested i just block in Spline. I got all 'Well I hate the layered method no way man!' But then he explained a bit. He told me not to change my method of blocking but for two things; Keep the GE open right next to you as you're blocking, and switch the tangents to spline. So i still blocked out my scenes the same way: Pose to Pose, Breakdowns, Flipping between keys, all exactly the same way i would do it in stepped. In fact, when I playblasted my scenes, I would still switch to stepped for viewing. The only difference is the keys were in spline and because I had the Graph Editor open next to me I started to understand what the curves were doing.
I can't tell you how much this improved my workflow and my work in general. The big surprise however was how much it really sped up my work. Having the GE open while i worked and seeing what the splines do when I'm trying to hit my poses was a huge thing. Reading about the graph editor is one thing, but seeing it work on your poses in realtime is a game changer. I don't spend nearly as much time freaking out trying to fix things in the polish phase anymore because i don't break things to start with. As a bonus, you can see when something is gonna cause a problem later down the line. That means less chance of breaking things (or hitting gimbal lock) when you get to polish. HUGE TIME SAVER. I also learned, though the computer is still horrible at animating, it's not as useless as you might think. It'll often give you decent starting places. Not having to do breakdowns on every control completely from scratch is another HUGE TIME SAVER.
I've used this method ever since and it still serves me well. When i first tell people i block in spline they often freak out until i explain i do things exactly the same as a stepped technique. Most people I've encouraged to give this a try found it pretty helpful themselves. There's a million workflows out there and no one knows which will work the best for them. But if you're struggling with the graph editor and looking to try a more efficient workflow, give it a try!
Animator, artist, musician and all around pretty awesome guy.