I have 1 Youtube channel and plan on adding a couple more over the next few months. I'm going to create the additional channels from the same Google account. It seems like way less hassle. And by having them all on a brand account, it's easy enough if I ever got to the position to sell one of the channels and transfer ownership to a new owner. I'm also going to funnel all the emails to the same email address so I don't have to keep switching accounts every time. Saves having to check multiple email addresses when, especially when the channels are new with few subscribers, they'd probably only receive sporadic/infrequent emails.