I do personally agree with the studies done and agree that it is hard to narrow down on just the right topic. I usually have to spend a while figuring out what I will be able to find good information on and also helps me to do a topic that I am already familiar with. And that is how I manage speech anxiety is by making sure that I'm not picking out a topic that is brand new to me and something I know nothing about. when speaking on something you enjoy or like to learn about it really helps me to focus and get a lot more done and prepare way better.
I agree sometimes I struggle to narrow done on the topic that I want to do research in!