Mostly I've been wondering if you ever take into consideration the person you're going to give feedback to? This isn't so much about the whole "oh, they're a BNF, they'll get plenty of loving from elsewhere" trend, but it is tied into it. Because I do wonder if people think "well, you know they're going to keep writing, even if we don't say anything" or "by golly, I need to encourage this young whipper-snapper!"
Basically, does what you know of a person inspire you in whether or not you give them feedback? Even though I generally give feedback on everything I read (thinking that, as someone who isn't a voracious reader, I owe that at the very least), I know that I am more likely to be compelled to do so for people I consider to be close friends - as a matter of support. Then I also know that I sometimes think that certain people probably have the confidence for my non-remark not to make much of an impact on their lives. Are others like this too?
We all have to pick our battles, and sometimes, you know, you just can't think of anything to say. Do you spend a while actively trying to think of anything for those writers who you believe need encouragement, or do you say to yourself that the writer in question will be okay because they're one of those determined types? Or can you happily and easily distinguish between what you believe is a good story and the writer in question? Do you only provide feedback based on how the story affected you, and not external matters like who happened to perform the inkshedding?