all the time
I use a sledge, wedges and maul, and last year bought a fiskars super splitter which I *really* like, it is a good design and they aren't hyping it, it works. I pretty much know now which chunks of what wood the fiskars can handle easy so try to use that as much as possible, it's just so easy within its design criteria framework. So far, it will split anything I can pick up and put on the chopping block. Some though, really twisty nasty stuff, I'll chunk up with the saw or use the wedges and maul, just depends on how really nasty the wood is. the fiskars is good for easy wood to just this side of nasty. Stay within that range and it is great. It's fast, I can't load a power splitter faster, I really can "john henry" beat that thing with the fiskars for most of my wood I cut.
I have one gas splitter here that my boss loaned me, but haven't used it for more than a year now (mostly needs repairs anyway, but I hardly ever used it before either, just rather hand split as much as possible..big fun for me)
I also have a simple rule with firewood, I don't waste nuthin. I frequently wind up burning an entire tree. When I saw, thumb size or larger gets cut. Anything that *can* fit into the heater without splitting gets stacked and used just like that. If I need a better balance of smaller stuff to larger, no probs, just cut more wood. The farm I am on is 800 acres, we do not lack access to cutable wood. Cutting the extra small stuff is not that much harder and I can milk a really large pile out of a tree with a tiny saw and just a few sips of mix. sawing is fun for me, splitting is fun, so I see no need to waste wood just for an excuse to run a larger saw..that's the sort of thing gives rural folks bad names in the popular press and mindset, wasting and overly polluting and stuff like that. I love nature and use nature, I see noi "profit" in abusing nature and being a jerk with what we have. Just like I won't waste petroleum fuels for "powersports" toys. I want five generations from now to be able to have some fuel. I have just as much fun going for a walk with the pets as I would making mud ruts with a engine powered toy. I use equipment, trucks, tractors, etc when they are needed, but that's it, I don't "joy ride". Boating..I've caught just as much bass running from an old tiny five horse outboard on a small boat as just about any of those yahoos with skiboats they claim are "bassboats".
anyway, back to wood:
Bigger stuff gets split. Left over branches I will wait until they are real dry, like next year, then bust them up with my hands and bring them inside in a bucket. In the summer I just stop by the brush pile and bust some for a few minutes and throw them down in a pile for the fall/winter. Takes like 60 seconds to get a bucket of dry twigs for "instaheat" fires either early AM or in the evening at dinner time when I come in.
I see some folks go to cut a tree and throw away half the wood, just abandon it or burn it in a pile, a bonfire..I just can't be that wasteful. All my earlier wood burning as an adult I cut with a handsaw, a 30" bucksaw, and my only splitter was my limbing ax, so I just learned to not waste anything, works out really well, and I learned speed and focus was more important on splitting then brute force most of the time. You get a lot more BTUs from a tree for just a scosh more of the easiest work, plus you don't have to split as much..you already get the smaller sizes when you milk a tree out.