I've not historically been much of a cocktail drinker, but I discovered the Negroni a while ago and find myself having one most nights before dinner nowadays. This got me to thinking - since the drink is made only with bottled spirits and has no fresh or carbonated ingredients, is there any reason I can't take a clean 1.75 liter bottle, fill it up with equal parts Bombay Sapphire, Campari, and Punt e Mes, and pour myself a perfectly proportioned cocktail of whatever size I like each night 'til it runs out?
That would be nice for my wife too, who enjoys one occasionally but likes them smaller than I normally make them. She could take just a few drops even, if that's all she wanted, and still know she was getting a balanced blend of flavors.
Is this something that's "just not done"? If so, is there a reason? Or is it common practice among regular drinkers of spirits-only cocktails?