Relying on convention is a good thing, as long as your team (and the larger community for that language) is mature enough to have a strong set of relatively easily discoverable conventions.
Strongly agree. Conventions can produce code that is easier to read and to write. Certainly to the uninitiated, most of the formulas in a math or physics textbook look completely opaque. But by following conventions on meaning of symbols, they are precise and expressive and also easier to write.
I'm not saying convention is bad, I don't think that at all. I'm saying that the two examples here aren't good advocates for a general principle of short local variable names. The examples work only because people already know what they mean, due to the pre-existing conventions.
