Frequently, I think. Isn't the whole point that it can be edited and
updated continually, unlike a printed book?
And isn't the whole point of my rant (resisting the temptation to type this
next phrase in upper case) the fact that *anyone* can amend *anything* in any
Wikipedia article, with nobody questioning the amendment until someone notices
the inaccuracy? As far as I'm concerned, that renders it potentially 100%
unreliable. If it leads you to a source that you trust, well and good. But you
could have found that source yourself.