Parabellum
I too was of that school of thought. After 12 years, the 'Angels' Drop,' or evaporation would outdo the extra flavour from being longer in the cask. Then, at a Whisky tasting, I compared my favourite, Lagavulin 12 YO, with Lagavulin 18 YO. The difference was substantial, as both my sons agreed. Being well brought up, in the Celtic tradition, both my boys are connoisseurs of good Malt and good wine, amongst the other finer things in life, and I value their opinions. (Don't always agree, though.)