For recipes, I prefer to use approximate round figures when talking in terms of metric and American customary. So, 1 fl oz is 30 ml, a pound of flour is 450 g, etc.

These are much easier to measure, scale, and remember. There are very few contexts where minute differences matter, and I don't think you're going to find a material crossover figure between those that want recipe help and those that are working on the kind of stuff where it matters.