Enjoyed reading this. I'd like to point out that Gin ABV varies with brand, spanning generally between 40 and 47%. This is going to have discernible influence on how a given ratio of Gin/Vermouth/ice dilution is going to taste.
Ratios should be viewed as guides, then fine tuned as to Gin ABV. [I'll add that your jigger is an invaluable aid].
A 40% at 4:1 is going to hit differently than a 47% mixed at the same ratio.
I carry a list of likely to encounter Gin brands when drinking out which I can refer to if my favoured brand is not on the menu. Check the ABV and order my ratio adjusted appropriately.
