Rotating out old black brood comb — does everyone actually follow the 3-year rule?

Fourth year in Devon and having a comb reckoning. Some of my brood frames are from my very first season and they've gone properly black — heavy, opaque, can't see light through them at all. I know the theory: old comb accumulates pathogens and pesticide residues in the wax, and cocoon buildup shrinks the cell diameter so you get slightly smaller bees. The standard advice seems to be replace brood comb every 3 years or so, which works out to swapping 3-4 frames per box per year. But when I look at how the bees USE the old comb — the queen lays it up wall to wall, they seem to love it — pulling productive frames feels wasteful. So, honestly: do the experienced folk here actually rotate on schedule, or is this one of those rules everyone quotes and nobody follows? And if you do it, what's your method — edge frames out, forced through the season?