This is a very hard field to work in, psychologically, because there's no reliable process for producing valuable work (this might be true generally, but I get the sense that in the sciences it's easier to get moving in a worthwhile direction).

I think you're right that philosophy is particularly difficult in this respect. In many fields you can always go out, gather some data and use relatively standard methodologies to analyze your data and produce publishable work from it. This is certainly true in linguistics (go out and record some conversations or whatever) and philology (there are always more texts to edit, more stemmas to draw etc.). I get the impression that this is also more or less possible in sociology, psychology, biology and many other fields. But for pure philosophy, you can't do much in the way of gathering novel data.