wow, i've def experienced the pattern you just described, but you actually seem to cover more ground than i usually do before eventually not arriving at your goal, but... you have enriched yourself in many other ways during the exercise. there is an explosion of facets in this field, and it is true that if you attempt to ride the cutting edge of everything you will probably never get to the killer app. you will however be well versed and an excellent resource for hire. i guess if you really want to get to the killer app part, you need to just work with a stack that you have already invested the time in to become proficient (the been-there-done-that stack).