Maybe I'm thinking about this wrong, but I'm not sure I agree that burn times are a myth. I think there are (at least) two different ways to look at burn time, one of which is helpful, and the other not so much.
1. Length of time a full load will keep my house at an acceptable temp - this probably involves too many factors that are specific to a house/installation/user preference to attach a number to a stove. Shoot-straight, I know your intent wasn't to provide a review of your hearthstone stove, so I'm not at all criticizing your post, but the below quote is sort of an example of this approach to burn time. Someone might read your post and assume that your hearthstone stove would only give them 3 hours of sufficient heat at at time. In reality, the stove only gave you 3 hours of sufficient heat, according to your requirements.
2. Length of time at the end of which I will have enough coals to reload on without kindling - this involves some variable that are not specific to the stove (type and moisture content of wood, draft), but with some caveats, I think it is possible to assign a number to a stove, and I think this number is very helpful to prospective buyers.
Personally, I wanted a stove that could consistently burn 10 hours at a minimum (using second definition). Eight hours seems to be typically considered the minimum for an overnight burn, but that means loading the stove has to be just about the very last thing you do in the evening and the first thing in the morning. I wanted more flexibility than that. If I wasn't able to evaluate stoves using the second definition, I think I could have ended up disappointed with a stove that didn't meet our wants/needs.