In a work by Leonarda (1693) I find that there are octave leaps at a cadence with an accidental sharp on the first note but no explicit accidental on the lower note. Surely the lower note should also be sharpened but this wouldn't appear to be the case in modern scores. Comments?
In answer to the question -'Do they?' it's no. Not currently, nor for two or three centuries. However, back in the day, over three hundred years ago, things were still being formulated, and I guess composers weren't as vigilant as they could have been. Maybe Leonarda realised that anyone worth his salt would know by listening whether the octave note should be an exact octave or not.