This is actually bad advice. Other than for convenience's sake, you want to RE one at a time. Otherwise you will end up with an excess of lower quality items if you happen to succeed earlier (if you craft 5 and suceed in the first try for example). The expected number of tries is the same whether you do 5 at a time or 1 at a time.
I tend to do this when I am crafting while online, especially green quality looking for blue. I setup one or two companions to craft one green item and as they come in I RE them. If I get the blue schematic I want I cancel the rest.
That being said, I do often kick off a bunch of crafting before I log at night, especially blue quality. Since the RE chance is halved and there are more purple schematics to get (for synthweaving and armormech), I am confident that having ten waiting for me will not result in "wasted" materials.