Yes, but when I first started using SkyDemon I think I found that it would remove frequencies that I did want to use. As a result I've always left that turned off, and I go through the printed plog and highlight the ones I will be using.

Typically within the UK your flight will fall under far more LARS units than you would actually talk to. The option to eliminate redundant frequencies attempts to shorten the list by removing those you are less likely to use.

It's been discussed that the ability to edit the plog after creation would be good. I don't think I've ever had a plog that wouldn't fit onto a single page yet, so haven't really dug into this in any detail.

You're quite right, unchecking that box does reveal the Farnborough LARS frequency, along with some genuinely redundant frequencies (and making the plog too long to print on one page). I wonder why a LARS frequency would be considered 'redundant'? You'd think LARS frequencies would be generally considered essential.

Have you ticked the 'Eliminate Redundant Radio Services' option in the printing options? I always turn that off, I'd rather decide what's redundant myself.

I'm curious how SD chooses which radio frequencies to show in the PLOG. For example, for my regular journey EGTR-BNN-OX-EGBS, I get every known frequency for Northolt, which is in the opposite direction of travel and is a highly-restricted military airport unlikely to have much GA interest, but no mention of the Farnborough LARS frequencies. Generally, but not always, I find myself having to write the LARS frequencies in by hand.