Ugh. The last sentence of that blog advice indicates Holley is really losing it in terms of technically knowledgeable people. Its too bad.
As for the rest, Holley has suggested using 1/2 of idle vacuum in their aftermarket publications years, although occassionally instead they suggest a PV rating half of highway driving vacuum.
Its one of the few bits of guidance from them that has no connection to engineering or science. Given no other option, maybe its better than nothing. ....
