I've been brewing for about 2 years now and never worried about a yeast nutrient and always just did a raisen boil "yeast nutrient" for the higher alc./wines. It has always worked fine for me but a couple nights ago I brewed a batch of Rogue Brewery Hazelnut Brown Nectar (SG-1.063) used a dry yeast (part of my experiement), activated the dry yeast with a bit of DME and yeast nutrient(just a dusting at this point) just before I started brewing, and pitched the yeast and yeast nutrient and 6 hours later the brew was already starting a bit and by the time I came home for lunch (12 hours after pitching yeast) I had to switch from my airlock to a blow-off hose! My carboy has a lot of head space too. Here it is about 48 hours later and I've had to switch to a larger cup, clean the hose, dump the cup of water/carmel looking milk a few times and it is still going at a bubble a millisecond! I will never brew without yeast nutrient again! Can't wait to see what it will do with a liquid yeast and a high SG!!! Moral of the story, if you see a trick, try it, it is usually worth it!