Mountain of salt, I'm neither published nor an industry professional: I find QueryTracker to be very helpful as one of my starting points building a list of potential agents to query. For novels that hit home as if their agent liked this, they might be interested in mine I do research those agents, but that research includes QT. But sometimes they've repped that specific author for 10, 20, 30 years and that's no longer the type of mss they're looking to add to their lists, sometimes they're no longer open to unsolicited queries, etc. There are a fair amount of resources available to us--including those like QT and Bewares here on AW that give us a peek at recent experiences of others, then there are the agency websites/agent blogs, #mswl, agent twitter feeds, recent interviews available online. IMO it makes sense to use as many of these as possible for an informed, targeted list.