I've been blogging for a long time (14 years?) and do it mostly for my own enjoyment. I did it long enough with few paying attention that I don't mind continuing with our without an accurate perception of value. Intrinsic motivation is always a better driver for creative activity than extrinsic motivation.
As to what is "valuable," I figure splitting some things up like this may help me continue to understand my views on that as well. It's constantly evolving over time.