I had my light crap out at 6AM one winter morning while it was still pitch black out. Fortunately I had a spare (nowhere nearly as many lumens however, but enough to get me to the office). It wasn't as bleak as I make it sound - while I was in a park with little lighting, there was a 7-11 type of place within 100 yards of where the light went out.

Without the spare would have gone in for a cup of coffee and waited until the sun came up, but in reality the thing could have crapped out a few miles further up the road where such options weren't as readily available.

This got me wondering about other types of things that might go wrong. For example, how much harder is it to fix a flat in the winter when the rubber is stiffer and all the tools are cold as can be?