I don't use Lightroom either, but don't need it to know that the Mk I 16-35mm is (by far) my most used lens.
Just a thought - for anyone shooting sports, it's possible that you could use a long telephoto to shoot several hundred pics at a single game. Yet you could use a different lens a few dozen times for other things and still not shoot as many pictures.
So maybe 'most used' lens might be different from 'most frames shot' lens... if that makes sense.
Might be better to count the number of occasions or places you use a lens, rather than the number of shots taken.
I'm a birder. Have used this lense exclusively for over 4 years. So far no one has chosen this lense. For quality, contrast, color, sharpness, auto focus speed, and lightweight, and price. Canon 400/5.6.
For me, the 15-85 was what I used most on my 7D, followed by the 100-400 and the 24-105 when I wanted a walk-around lens with just a tad more reach than the 15-85. I used to have a 100-400 back when I had my 10D but I sold it during my 20D days and didn't have one until early 2011. I love having it again and have been using it more and more.
Took a quick look at Lightroom, and for 2011 the 100-400 L was most used, with the 300/2.8 L II being a close second. My 300 arrived Sept. 21, so it has clearly been my most used lens since that day. The 24-105 L was third, whereas in some previous years it had been first, mostly because of event photography.
My least used lens was the 15 fisheye, but I'm still keeping it. In 2010 it saw a lot of action, and who knows, that could happen again in 2012.
but its a wonderful lens! 