^^ I don't really recommend pre-emptively taking a benzo as it will reduce the psychedelia. Plus it's healthy to work through anxiety. Now, if the anxiety gets horrible during the trip and you can't deal with it, a fast-acting benzo can be a good solution. I do feel like people often jump too readily to benzos... unless you have an anxiety problem, anxiety can generally be dealt with and once you get past it you're a stronger person. In the majority of my anxiety-filled trips I was glad I went through it afterwards because the trip resolved into something beautiful, but if you abort that process, that doesn't happen. Maybe no harm is done, but you might have denied yourself a beautiful and strengthening experience.
I'm not saying there is no use for them or no value in having them on hand just in case but just because you're feeling anxiety, that doesn't make it a bad thing.