How Many E-Mail Addresses Do I Need For Tiered Projects ?

I'm using tiered projects and I only use 1 e-mail address for each tier. Is that enough or do I need more and why?

each email account is an individual person, you could run your tier one projects 10 times over and simply changing your email and content, this means, 10 people have written about your site, meaning more links from different people..

I normally run my lists at least 3 times over with 3 separate emails for a good amount of tier one links, for the other two tiers I use quite a few different emails, around 15-30 emails for a tier 2 project and my tier 3 emails are normally junk emails which I have a master list of, these are previously used and abused emails I've simply saved as I post to comments, trackbacks, microblogs etc so I don't even think emails matter.