Ok, for those of you buying & using site lists and indexing service together, I'd like to give you some tips to help you save your hard earned cash.
1. Never send backlinks that also have other people's links on them (e.g. blog comments, image comments, guestbooks etc.) to indexing service. Why? Because these same people (you know there are many!) that are using the same list as you will already have done just that. So why bother wasting your time sending the SAME backlinks to indexing service again? Someone else is already doing it for you!
2. Never send backlinks to indexing across different projects. For example, if you've just bought a new verified list with 30k targets and you use it for your 10 projects and have them all send backlinks to indexing service, 30k SAME backlinks are being sent away TEN times to your indexing service - a total waste!
3. Try and send only contextual backlinks that have their own pages (articles, web 2.0's, social networks etc.) to your indexing service. These are your true unique backlinks that need all the attention from search engines. They carry backlinks that ONLY point back to your moneysite/tiers.
So in short, the more people are buying and using the same list, the less need for you to use indexing service as these people will already have unwittingly done you a huge favour :D