I've had many 3 of 5 and 2 in a row streaks.
But there is another human factor to consider in "win" streaks: getting a schematic but one that is not desired e.g. all the Presence purples, or Redoubt Cunning blues, or worse a player is looking for a VERY specific purple and not getting it until getting the other three or four. Many - if not most - players in those situations will emotionally consider those successes as failures.
Though I don't consider learning any schematic as a Fail. I Agree w/ the Point Psandak is making. SolQitta my Healer is also my Armormech. I craft all of the gear that she wears so I want very specific Purples. Because I am looking for Expert
for her to wear it can seem sometimes that RE'ing is being less productive than is actually happening. In the end all you need is patience (& have a love of WZs or a 55 toon to run dailes & give you a never ending supply of credits for which to keep getting supplies to make the items to RE till you get what you are looking for).