I operate multiple sites - they all belong to the same topic. Now try to get what I mean. What we have: 5 sites that need to be promoted 15 sites that have unique content designed for promotion of the previous 5 - all different countries servers Question: If I link from all the 15 sites to the targeted 5 - will Google find a filter to minimise my efforts? Meaning the EACH of the 15 sites links to the same 5 sites...
Yes Google could catch on to what your doing by various means. If it was me I'd make sure there is no foot prints across the 20 sites. In other words, remove any signs that could prove every site belongs to the same person. I'd also build the links over a slow period of time. Thats me being paranoid but that's how I'd tackle it.