What I meant was that the result of the .. terms are compared to $. if the terms are numeric. For example:

  while (<>)
  {
    if (1 .. 10)
    {
    }
  }
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Will print lines 1 through 10 of the input, by using $. to compare to, which is 1-based.

$. doesn't go anywhere if you are not using <>, it just doesn't get reset and incremented. Furthermore, incrementing it yourself is probably not a good idea. Who knows what other (called) code might use it.