For a lot of ingredients it's simply not going to be possible to follow exactly. For instance, suppose it calls for "1 jalapeno, chopped" - jalapenos will vary

For a lot of ingredients it's simply not going to be possible to follow exactly. For instance, suppose it calls for "1 jalapeno, chopped" - jalapenos will vary greatly in size and heat. Other ingredients will lose potency over time, so who knows how yours compare to theirs. Another problem is that many recipes use the wrong metric for ingredients in the first place - most things should be done by weight, not volume. But yes, in terms of cooking (as opposed to baking) one should never expect to follow a recipe exactly, no matter what. Everything should be tasted and modified to adjust along the way. Eventually one gets a sense of what those phrases really mean, particularly if you see the same person's recipes repeatedly.