Has anybody mixed regular filler and polyester together?

[KTJMcG]

Was looking around youtube thins morning and came across this video. He mixed up some filler then added polyester finishing filler to it and then spread it over his first coat of filler. Never saw it done like that before. I was wondering if anyone tried it.
http://www.youtube.com/watch?v=5vNXxRPL ... re=g-all-u

 

[SELLERSRODSHOP]

i've seen some of the old timers add a little fiberglass resin to filler, but really see no need to mix poly in with it. fillers have come such a long way in the last few yrs that i dont notice as many pinholes/bubbles like the old stuff. i usually just mix a little poly & smear it with a razorblade over any pinholes. cuts down the sanding time that way.