he's right it will accelerate the fermentation. But in a good way. yeast double is size every x amount of time. Once it hits a certain density it's all about taking sugar and making alcohol and not reproducing. That's the point you want your yeast stain to be at. Less stress on the yeast yada yada. I'm sure there is such thing as adding to much yeast. But that won't happen with 1 gallon and a packet of yeast.