There's a few modernist cooking tricks that require small amounts - tenths of a gram - for big impacts. Sodium citrate can make any cheese melt beautifully into a smooth sauce, using something like 1% of the weight of the cheese.
Any juice can take the roll of lime or lemon (in cocktails or baking) by adding a bit of citric or malic acid. Orange juice is 1% citric acid, so add 3g citric and 2g malic per 100g juice and now you can make an orange daiquiri or "key" orange pie.
Emulsifiers get goopy if you use a lot, but can make a smooth syrup in small amounts. You can make a nice syrup from any nut milk with a small amount of xanthan and gum arabic.
There's a wide array of ingredients including xanthan and gum arabic used in tiny amounts in gluten free baking
I sometimes wish my scale was precise to below 1g when measuring yeast for long-rising (bread) dough. A recipe may ask for 1g, and adding 2g will make a huge difference.