As I'm getting older, I couldn't hit my irons well anymore, so I tried changing shafts randomly, but nothing felt right.
I saw Slickson on YouTube and tried it at a local off-market store. It was okay. The advantage of Slickson is that there's no shaft upcharge, so you can choose any shaft, but the shaft I wanted to try wasn't available for fitting. Other brands didn't have it either. (Something like Graphite 75R S)
So, I went through the most expensive fitting program (free if you buy an iron set) at Dunlopp Center in Cheongdam, which is more expensive than local stores, and tried various shafts. I finally chose Graphite 75R. (While going on a family trip to Seoul from the provinces)
It took me two months to adjust,
but my irons have become much easier to hit lately. First of all, I don't need to control the distance as much, and the dispersion is wider, but the percentage of regular shots has also increased.
And changing my practice method seems to be helping too, but I'll talk about that next time....