Yes, I realise my wood is a fair bit bigger than that of most blokes
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We put a bigger heater in our 'new' house compared to the one in the old house and the size of the wood I use grew proportionally. Bigger wood (less surface area for the same volume) means slower burn and heat production but it's not hard to get the baffle plate in the heater glowing with the big wood and the flue doesn't clog with creosote and doesn't smoke except at start-up. So I figure that the bigger wood is fine in my particular circumstances and if I split it smaller then that's many more pieces I need to pick up and stack (that's prolly the main factor). Most of the wood in the shed would have been split to half the size back at the old place.
When I was researching heaters for our new place I read some stuff that said 10-15cm (4-6 inch) wide firewood was the most efficient for heating but who really knows?