>>9534358"Quarter Cask" refers to the size of the casks that the whisky is matured in (rather than the strength it is bottled at).
It ensures that a greater proportion of the spirit is in contact with the inside of the the cask, thus absorbing the desired flavours & aromas from the cask more rapidly and intensely.
I do have a bottle of George & J G Smith's Nadurra Cask Strength Glenlivet secreted away in my cabinet alongside my private bar, but for everyday drinking I usually have a bottle of Laphroaig Cask Strength on one of my optics behind the bar, for easy access, because it is my favorite (by far) compared to most other whiskies - the one exception being Lagavulin 16 (year old), that I like equally on the grounds of nose & palate, but sadly I typically have to pay about 60% more for the Lagavulin compared to the Laphroaig. No problem though - I have a bottle of Lagavulin hidden away alongside the Glenlivet etc. in my spirits cabinet.