chasv77answered grow question 4 years ago IMO, if your fan leaves are starting to yellow (not a nutrient issue), then it is ok, to trim.
Removing yellowing leaves, just speeds up the process, that the plant would do normally.
If they are good, and you want to expose other covered bud sites, then do that sparingly.
See my diary, for results of my trimming, if you so choose.
Point is, if the leaves are looking good, don't trim, unless it improves the overall heath/quality of the plant.