The documentation expressed a concern about not linking both miles and chains because miles are "common units".
However, many of the articles which use miles and chains do so several times in that one article. Using this template each time will result in duplicate links to chain (length) each time, a far more egregious violation of WP:OVERLINK than linking miles once would ever be.
Furthermore, there are many cases in which miles should be linked. Being common doesn't make their meaning clear; they are, after all, ambiguous units, with many variations over time and place and context; often that link should be specific, such as [[statute mile|mile]] causing it to go to the appropriate section of the mile article.
This template claims to "mimic convert", but does not does it well. If it did you'd have to explicitly turn the linking on when you want to use it, it would allow adjustment of the precision (some uses of this unit might have fractional parts of a chain, or might use miles and chains with only be 10-chain precision, so the results should be adjusted accordingly), it would allow abbreviation of the units (especially useful for those infoboxes listing the distance in miles and chains at various waypoints), and a few other things. Gene Nygaard (talk) 05:48, 8 February 2010 (UTC)[reply]
(Belated reply) - the purpose of this template is solely for where it is required to link chains but not miles. If it's necessary to link both, or neither, then {{convert}} can be used in the conventional way. Hence I would imagine this template only being required once in an article. Convert can also be used for precision cases if required, though most sources giving miles and chains wouldn't use fractions of a chain (they'd use miles and yards for instance), or 10's of chains (just fractions of a mile). Anoptimist on the run!11:42, 25 January 2013 (UTC)[reply]
