Most optical cabling setups I encounter these days tend to be made so that you just use a straight through (A-B) cable, and it generally just works. Although i

Most optical cabling setups I encounter these days tend to be made so that you just use a straight through (A-B) cable, and it generally just works. Although it is super easy to just pop the individual fibres out of the clip holding them together and flip them round. The biggest polarity issue I see are with mtp/mpo cassettes, especially with multiple spans, you always seem to need to cross something there.