Lots have. I agree though it's not a good idea in most cases to set an abitrary time limit. My longest was 30 days, and since I've been here I've done a 14 day fast and many short ones, 11, 10 days and less. I mostly do dry fasting now as well which is more intense as a rule. I've done many 5 day, a couple 6 days and one 7 day dry fast.
I do think it's important to keep them open-ended and it's more important by far to break the fast properly than it is to reach a particular goal of days.