I keep my computers a long time, too. Mine is from 2014!
I still got dual-channel though. I figured if I want to upgrade later, it’ll hopefully be easy enough to sell a 2x16GB kit to someone else on the marketplace and buy replacement 2x32GB kit. Don’t want to give up that dual-channel performance for many years in the hopes of saving a buck later. Moreover, RAM will likely be cheaper in the future anyway, so it’s possible a 2x16GB kit today and a 2x32GB kit in five years will be cheaper than 1x32GB today and 1x32GB in five years.
I see the potential cost savings as a wash, so don’t see a point on ever giving up the dual-channel performance.