It depends very much on whether I think the tea is bad or my brewing skills are to blame.
My first and only order of Taiwanese oolong from Tea from Taiwan literally went down the garbage disposal after very few brewing attempts, all $66 worth. In comparison to similar tea from Hou De, it didn't take long to see that this was very bad tea. Many are happy with their TFT purchases, and maybe TFT made a mistake on this order, but this stuff was terrible and not worth any additional time or effort.
On the other hand, I've struggled quite a bit with O-Cha's Hatsumi shincha. Knowing the quality of this vendor very well, and how tempermental shincha can be, I kept trying until I finally got acceptable results. Thanks to Chip and several others for offering suggestions that were helpful in conquering this beast. Although still not my favorite of the five shincha I tried this year, IMO it certainly belongs in the company of the others, providing one has the persistence to see it through. I don't blame those who give up, but I feel the extra effort was worth it.
Of course, I'm drinking Hatsumi as I write this.