I'm not sold on the personalization. The personalized queries I've sent have, generally speaking, fared neither better nor worse than the non-personalized queries. To really personalize a query is a lot of work -- maybe you go read some other books they represented, or spend hours reading their tweets and online interviews. Then you do all that, and you find actually you've gotten nothing that can help you. Or maybe you do and you make your query super personalized -- and they still reject it
I read agent profiles and if I see something that seems like it would help make my query more personalized then I do -- like: You used to work in an art gallery and my query is about an art gallery. But I don't go out of my way to learn about every agent. Your chances of getting representation are so low with each query, it's not really in your interest to spend ages researching an agent just to try and have a more personalized query. If they like your story and your query, they will make a request. If they don't like it, they won't.
I have queried agents who seemed like they would be perfect match "on paper" and yet I got no response from my query.
Like Constantine mentioned, agents have different opinions on how much to personalize. There's no one size fits all.
You have to remember that there are so many unknown factors in play when an agent reads your query, the personalization is likely minimal compared to those other factors.