I have 3 but i'm only ever activly using two of them.

I have admin @ terminalskunk.com & terminalskunk @ gmail.com as my two main checked (both are setup in thunderbird)

I also have a third email address which i use to keep emails i don't need in my main mailboxes any more, I also use it to sign up for junk that i'm only going to use once or twice.

i say one cause theres really no point in having more then one accounts on anything unless you need one for business reasons like me and one for personal then 2 but mostly you only need one

You should have an Email for personal stuff for example (Bank Payments & Loans etc) and another one if you've a business and then another for Gaming etc.

Also, I suggest using LastPass to encrypt all of your passwords so nobody can grab hold of them.

Back when I did youtube I had 3 but usually I keep two around one for Personal and IRL things and the other for my online Alias.

I have 3 but usually only use 2.
School
Personal
Spam

I have one that i use for everything. Probably shouldn't though.

There isnt a specified right amount

I mean, I have 5/6 Emails but the old ones which I still get spam from I have linked to my main one.

IMO, have as many as you need aslong as you can remember the address' and passwords to all of them.

I have one for business and one for personal, anymore than that is unnecessary i think.