As most users will use both sides of the blade during a shave, the 3 shaves would be the total number.

For me, with Derby's, 3 or 4 shaves per blade. There was a thread going on at B&B started by Dave Irving who decided to take a DE blade and strop it before each use (IIRC he was using a stropping device designed for either old DE blades or the single edge wedge blades). Last I looked in he was at 29 or 30 shaves on the blade.

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