I split about 20% of my wood real small just for starting fires, I made the mistake my first year heating with wood of only having big hunjs of wood and I had the hardest time geting a big chunk of Oak started from a cold stove and even from small coals, if I did not get up in time in the morning and the coals were low getting a big log going can be a real PIA. I was out in January re-splitting logs to get smaller peices to start fires with.
Plus smaller the peices quicker it dries, so the people on the board that are not sure if their wood is dry enough, try respliting the wood so there is more surface area exposed to the air and it will dry faster.