I've read the many benefits and purpose behind copywork:
from The Well Trained Mind, "The purpose of copywork is to get into the child’s visual (and motor) memory the look and feel of a sentence that is corrrectly composed, and properly spelled, spaced, and punctuated. " ... "So you should do copywork as long s the child is still struggling with the basics of writing conventions: spaces between words, capital letters, punctuation, spelling. (Generally, this is first grade, although it should extend into second grade or as long as the child seems to need it.)"
from Simply Charlotte Mason, "Copywork is the method Charlotte used to teach and give practice in handwriting skills." ... "As the child carefully copies a noble poem, a Scripture passage, an inspirational quotation, or the lyrics to a hymn, he also absorbs grammar and punctuation rules."
from Higher Up and Further In, "Its [copywork] purpose is to improve the child's handwriting, expose them to noble thoughts, good sentence structure, rich vocabulary and introduce basic punctuation and capitalization rules. Even grammar is incidentally taught but this is just an added benefit and not the purpose for copywork."
from Ambleside Online, "Copywork done properly forces a child to slow down and absorb the punctuation details, notice capitalization, and internalize sparkling prose. For this reason, a child's own stories are not the most ideal source for copywork a la CM."
I feel that right now, having them do their English (grammar and composition) neatly, their Spelling neatly, and having them read (and listen to) great literature is covering all the aforementioned benefits of copywork.
It's very freeing to let go (but I still love Charlotte).