Many years ago, when I was starting the search for my current agent (after my former one retired), I took an online course on publishing. It was taught by an agent and her author. One of our coolest classes they led was a Q & A session. We got to ask them anything about publishing, about the process of querying, about what made agents say yea or nay to a manuscript. The agent was somewhat familiar with our work by that point in the class, so her answers were relevant and specific.
I was curious about comps: are they needed? Do agents require them? Do they help your book in any way when you are querying?