Is this SSR isometric tutorial wrong?

https://design.tutsplus.com/tutorials/how-to-create-advanced-isometric-illustrations-using-the-ssr-method--vector-1058

This tutorial states to scale shapes to 86.062%. When I do this the corners never quite line up. Its been driving me crazy. I think its a typo. Does anyone know the real answer? I have found if i scale by 86.62 it works better but still not exact.

Great design resource

100 Things Every Designer Needs to Know About People (Voices That Matter) Submitted March 08, 2018 at 10:46AM by geniemac86 http://ift.tt/2ts1YkF