I think you're slightly missing the point I was making. For normal real-time control, what you say is true.
But I was talking about the optimum start function, where the stat decides when to turn the heating on first thing in the morning, based on what it has previously learned about the dynamics of the system. It doesn't know whether you're going to light the wood burner part-way through its warm-up cycle.
Maybe mine wasn't working properly, but if I needed to go to the toilet very early in the morning, the radiator in the bathroom would often be hot - and I concluded that the stat was turning the boiler on a full 3 hours (the max time it uses) in advance which it certainly didn't need to. I've now disabled optimum start and programmed the heating to come on one hour before my alarm goes off - and that's always been enough, even in very cold weather.
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