How important do you think are Tier 3? If you build some quality Web 2.0 to your website, some HQ automated backlinks with GSA - are Tier 3 really necessary? Or could you see some changes in the SERP's because of the Tier 3 links? I'm wondering about that for a long time and would like to hear your opinion. Are you working with Tier 3 or are Tier 2 enough?