I definitely don't try to catch everyone. For one, I'm on a heavy mtb. And while I can sometimes catch up to groups I can't possibly hope to pass because the front of the pack is way faster. I don't like being a fool.

I will absolutely pass slower riders. 100% of slower riders are other commuters and hipsters on fixies. And I'm not doing it for exercise or for my ego. I do it because I am going a faster pace and I don't want to slow down. So, it's always happenstance.

It will be interesting to see how things change once I get my road bike.