How important are precision and completeness in learning definitions when expanding your vocabulary?

As an English enthusiast, I’ve taken it upon myself to expand my vocabulary further by using the spaced-repetition software Anki.

Some words have more than one definition and I sometimes miss one definition and/or stumble upon the exact wording of a definition when remembering it. For example, the word “fastidious” has the following defintions:

1. Difficult to please
2. Showing or demanding <del>great</del> excessive delicacy or care
3. <del>Having</del> Reflecting a meticulous, sensitive or demanding attitude
4. Squeamish

As you can see above, I crossed out the words that I mistakenly used in recalling certain definitions. Or sometimes I’ll forget definition #3 entirely. When I make this type of mistake in my studying, I move the flash card back to bottom of the pile to review again.

Am I being too fastidious in my studying? How important is precision in studying vocabulary? Is the general sense of the word enough? Could it be that you have to diligently study the precise meaning of a word in order to absorb a general idea of it?

These questions are of particular interest to me as a writer. When asked the definition of a word by a child, I usually cannot give him/her a precise definition of the word, though I can explain it well enough so he/she understands the nuance of the word. I find there are many words that I know intimately, including nuance, without having ever looked up the word in a dictionary. And yet, I don’t want to take the chance of not learning nuance. So I worry: if I don’t memorize all the definitions of words, and precisely as well, will I miss their nuance? Is having a general definition of a word enough?

Re-reading this question has made it agonizingly clear how anal-retentive I can be about certain things.