It might, it might not. I'd venture to say it mostly depends on the state of your yeast before you pitch. Have heathy active yeast, it may or may not make a difference if you add it or not. It probably helps an underpitched, slightly inactive yeast take hold of fermentation, but in the end, your beer will be better off with a longer fermentation anyway. Wake up your yeast in a starter, regardless.
Bottled: Old Peculier, Kumquat Kolsch, Dopplebock
Kegs: Helles, Oktoberfest, Hefeweizen
On Deck: English Bitter, RIS