Last.fm: number of tracks vs. time played

What I find a bit weird about how last.fm tracks listening trends, is that they only use the number of times you played a certain track. I always felt that this would favour bands that create shorter songs. A band with a average song lengths of 7 minutes will only get half as much scrobbles (in last.fm jargon) as a a band with average song lengths of 3,5 minutes. I used to wonder what effect this would have on my charts.

I must not have been the only one, because when I was looking at the build.last.fm page, my eye caught the last.fm normalizer tool. This tool will take your top 50 artists and rerank them according to the estimated time that you listened to them (more info can be found on the tool's site). Looking at my normalized top 50 artists, there are no big drops, but there are a few big rises. Wolves in the Throne Room gains 20(!) places, Red Sparowes and Evoken gains 15 places, and they are all in my top 15 now. This matches much more to my gut feeling of what I have been listening to the last few months.