Yes an interesting question for the fact if you force the check will it continue along the kerf into the pith. But if you let it naturally occur it is spread out, as in, not in a continues crack in the same plane. We are told the natural checks are not a serious defect, but could a forced check be? In a post I would suspect not, but a load carrying beam maybe.
On the other hand a check has no material removed from the section, it is just rived. Where a mortice or peg hole has removed wood from the section, this needs to be accounted for. Is the 1/8"x1/2" enough to be calculated and inserted into the equation? Maybe.
Tim
