Yes. In my real-world day-to-day job, quite a lot. Used to be constantly. Over the years I have realized, through repeated execution & work, that I really am good at the kind of work I have to do day-to-day, though that doesn't necessarily translate to being good at work on any given day.

In poetry I don't but I think that's because so much of my writing is about meeting my own expectations and no one else's. I also do it for pleasure so I am always trying to do my best. At work I feel imposter syndrome sometimes because I feel like I am not trying very hard, I am just managing to out-perform my peers, which are two very different things. I can turn in "crap" work so long as it checks certain boxes and be lauded; I think this lends to feeling like an imposter. However, at the same time, an environment where it is easy for someone to succeed/exceed their peers or metrics with minimal effort certainly does not encourage that someone to push to put forth more than that - the minimum or just above.

For me I think the imposter effect and the Dunning Kreuger effect must be linked in some way. The more aware you are of how well a task can be executed, the more you will see your flaws, even if those flaws become less severe in magnitude as your skill (and knowledge of the ideal execution) increase(s). I guess the missing step is where does a person go from knowing exactly how something should be done and how their execution is less than ideal, to thinking that because of this gap they must be faking it on some level. I surmise it occurs when there is a disconnect between the fawning audience's and the critical performer's opinions of the set (or show, or etc).

A lot of dedicated practice for your friend's recital certainly would not hurt your performance when the time comes. However, I would want to make sure that, in your throes of imposter syndrome, you do not spend that time fixating on small flaws only you are likely to notice and in so doing overlook larger or more pressing areas of opportunity for you or the piece.

Also of course if it's your friend's recital, and not yours, the pressure's on her performance way over yours. That may explain some of it?

The mind is a tricky devil and it is not always your friend. Don't allow the feeling of being a fake or fraud take over; don't give it credence or let it take root, if you can. It'll probably always be there, but that doesn't mean it's right. I like to remember that paranoia is really a twisted form of flattery and self-importance, when I get into my head: imposter syndrome is a way to tell ourselves we aren't worthy, don't fit in, or don't deserve objects/positions/awards, etc that, in truth & for the most part, we have earned and do merit.

The feeling is like a babbling voice: you can't help but hear it, however you should not bother to listen to it very closely.