Here are a few things that bother me when I see them in cocktail recipes, with my solutions on how to deal with them.
1. "Juice of one something-or-other" ("juice of one lime", "juice of one lemon", etc.) This is just asking for inaccuracy and inconsistency. The problem is that lemons and limes vary in size. No recipe should be written this way, in my opinion. If you come across a recipe written like this, here's my solution: an average lime contains about 1 ounce of juice; an average lemon about 1 1/2 ounces. Then be sure to taste the resulting cocktail to check for balance.
2. Sour mix. This artificially sweetened lemon-like concoction is the friend of the lazy bartender, and store-bought brands are usually chock full of artificial flavorings and colorings. Ugh! And many bars have taken to using sour mix in a Margarita, a drink that requires lime, not lemon. In recipes (other than those for Margaritas) that call for sour mix, for every ounce of sour mix, use 1/2 ounce of fresh lemon juice and 1/2 ounce of sugar syrup.
3. Jigger or shot. A jigger or shot can be anywhere between 1 ounce (at many cheapskate bars) to 2 ounces (standard shot at a bar I worked at several years ago). My opinion? One shot or jigger should be 1 1/2 ounces, and nothing else. This is how I learned it back in the 80s and early 90s. The 1 oz shot seems to be an innovation of the late 90s and 2000s. But without exception, unless your boss says otherwise, default to 1 shot = 1 1/2 oz (45 ml). If a recipe calls for a 1 oz. shot, it should just say "1 oz".
4. Wild deviations from norms. Nothing wrong with variations: bars and bartenders come up with their own special touches to drinks, just like restaurants and chefs do with dishes; also, many recipes evolve well over time. Recipes vary from book to book, and that gives the bartender room to experiment with. But some recipes change so drastically over time and from region to region that they bear little resemblance to the original. If so, its time to give the drink a new name. A prime example is the Mai Tai. Originally, the only fruit juice was lime, but many versions nowadays call for pineapple juice, orange juice and grenadine (not in the original recipe), and omit the almond syrup and lime. It may be a tasty drink, but it's not a Mai Tai. I'll give the Mai Tai a treatment in a future post. The only solution to this problem is to do research. Look at different books, check the Internet.