Rarely. Extremely rarely. Although, I think I have been well served in how much I generally avoid it. It has kept me pure of the taint of how much mediocrity is apparently accepted in fan fiction. Therefore, when I decided to go ahead and write a fan fiction of my own, I really put all my skills into it and went about researching the source material thoroughly and using my skills in style mimicry to accurately copy the original writer's writing style.
Also, the only reason I started writing it at all was because I actually had a good idea of where I would go with for a plot.
According to the reviews I've been getting, it seems I really did a good job with it.
(For those who I've made curious, it is a fan fiction to Mother of Learning, and I've made it a Royal Road exclusive because that's the only platform that I frequent and post to which also has Mother of Learning on it. I won't be posting it here unless and until Nobody103 posts the source material here.)