A recurring problem for me with grammar is my constant use of sentence fragments. It's not necessarily a problem I want to fix. Starting sentences with "but," "and,""so," no subjects. . .
I can remember way back to high school arguing with an English teacher about "But." I showed him several examples from modern literature wherein the author used,"But" at the beginning of a sentence. That old English teacher wasn't going for it. Wouldn't let me do it. See -- a sentence fragment. Dropping the subject. For emphasis, I suppose.
I've read too many modern novels and poetry. Did Hemingway effectively use sentence fragments? Yes. He wrote dialog true to our speech patterns Sure did. What about Stein, Salinger, Vonnegut, Joyce, Brautigan? Can't remember. But I'm certain it's from reading their novels and others that I picked up the habit.
It distresses, confuses, perhaps angers English teachers. Out comes the red pen and they start crossing out, adding subjects, putting "sent. frag." above "And" and "But." A lot of red ink used on my writing! So, is it a habit I want to break? Not for informal writing. But essays and academic writing? I now know better and can restrain myself, self-correct, take out the red pen on myself, edit. I am able to write full sentences, but it's with compunction and a sense of defeat.
Have I picked up patterns of spoken speech, used them de rigueur, with abandon, unconsciously, consciously? I suppose so. Am I sorry about it? I don't think so. Old habits die hard. Don't they?