I should have been more specific. My bikes all shift flawlessly. I'm more talking about riding other bikes in a pinch; whether you rent one or borrow one.

For example: I was at my parents' house last winter and was really trying to stick with a strict cycling program. My coach scheduled a ride and my only option was my Dad's Sora/Tiagra-equipped Specialized Sequoia (We're roughly the same height). It hadn't had an adjustment in who knows how long. Long story short, I was constantly between gears and throwing the chain. It was a very frustrating ride. Consequently, I hate crappy shifting.