Social bookmarks and social-network platforms can be useful components of a Tier 2 campaign when they are used to support existing verified backlinks. Their role is different from a primary contextual placement: they add variety, additional discovery paths and another class of referring pages around the first tier.
A lower tier is a natural place to broaden platform coverage. The main campaign can remain focused on its preferred contextual sources, while the support project uses a wider mix that includes social bookmarks and social networks. This separation keeps the primary target strategy cleaner and gives the supporting URLs their own promotion layer.
Social platforms also tend to use different page structures from article directories, forums and wikis. That difference can help diversify the footprint of the campaign. Some platforms may use a visible URL, some may allow an anchor, and others may create a profile or content page. The campaign should allow each supported engine to use the format it can actually publish.
Even in an automated campaign, short descriptions and article text should remain understandable. Content can discuss SEO workflows, backlink verification, tiered campaigns, link discovery, website promotion and campaign organization. A varied content set gives engines more suitable material and reduces repetitive titles.