Not consistent/significant enough to count possibly. I don't recall crafting or BGs giving experience...but if it was small enough to never notice, or I only did it at max level...then yeah...I don't know. Come to think of it, I never even paid attention to that. Hmm...
Here's how questing works:
You: Oh look, a heart! I should go to that and see wh...
*New Event Nearby*
You: Oh, what's this? Hmm...I should check this out. I'll make my way to the heart after it!
*Event A chains to B, C, then D is a boss*
-30 minutes later-
You: That was fun. Now, onto my heart quest...lalala almost th...
*New Event Nearby*
You: What the, cool, another. Much closer to the heart this time!
*Event A chains to B, and you also get half the heart filled in, chains to C*
-20 minutes later-
You: Aw no boss, but still interesting and fun. Now to finish the heart!
*See people jumping up something and going really high*
You: Hmm........................what are they doing? That looks like some sort of puzzle...
*Follow them to find out it's a jumping puzzle, not easy, and leads to a mini dungeon*
etc.
etc.
Though I guess you could ignore all the fun stuff and just do hearts