[ehsankia]

Yep, you should just use the best judgement, for example

    for distance, time in driving_metrics:
      speed = distance / time

is a lot clearer than

    for d, t in driving_metrics:
      s = d / t

even if it's used in a tiny scope once. But some things don't have a valuable meaning, or the meaning can trivially be inferred.

[SEJeff]

I meant i as in the iterator variable for a counter like when using enumerate() or a c style for loop where you manually specify the list index.