So I did the sensible thing to do and did what I should have done first: a Google search. These three articles at Lifewire, Audioholics and Audioreputation seem to agree that manufacturer sensitivity figures are an average in the 300 Hz to 3kHz band.I'll bet that most speaker systems have their sensitivity tested from 500Hz to 2k Hz, but I would prefer 20Hz to 20K Hz for full range speakers, 80 Hz to 20K Hz for speakers intended to be used with a subwoofer, and some standard range for subwoofers.
This means that subwoofer range is completely avoided in sensitivity figures, as they ignore the sub-300 Hz range. That also means that in practice, with a standard 80 Hz crossover, the system might use up more power to reach reference SPL than stated in sensitivity figure, because of the added load for reproducing 80-300 Hz content.
So contrary to what I thought, the real-life situation might not be *better* than what is shown in the spreadsheet, but in fact perhaps slightly worse (i.e. a speaker barely reaching reference levels according to the spreadsheet based on manufacturer sensitivity rating might not in fact reach it when playing lots of mid-bass for example).
Do you think I'm getting this right?