This is one reason I pretty much just leave classical music on in the background 16/7. I'm absolutely not abusing the service -- I'm paying a subscription for exactly the right to do this. And, it helps the artists who get most shafted by the aggregate play count payout model.
In other words, If I only listen to 'my favorite niche band' in a month, but don't use the service much, it's unlikely that they will see anything near the full possible share of royalties from that months $10. The system instead is biased to musicians whose fans use the system most heavily on loop - ironically more likely to be taylor swift type pop megastars.
[edit - explained more clearly by http://lit.vulf.de/spotify-so-little/]
Anyone know how apple will compare on royalties after the 3 month period compared to spotify? I've been a spotify premium subscriber since 2009, but would move to a system that meets my definition of equitable.