Anuj, your double cut method relies on the width of the second cut removing some of the error from the first cut, which it will, it could be repeated as required. For real wood however the edge finish from the saw is not as good as a planed edge that could produce an almost invisible join, depending on the grain.
As for edge joining plywood where half the layered wood is running the wrong way, the result is more cosmetic than structural. Your choice of epoxy was wise as a gap filling adhesive!