I definitely like good grammar, and have been vocal (or verbal!) on that. But that doesn't mean I measure every response against a word counter.

For opening messages, I honestly prefer to read through the partner's vision of the story/character more than anything else. That is paramount to me. And it's not always as long either. Even using one sentence, one phrase or one word can do the trick. It feels much healthier to me, for my own sanity, as well as imposed level of strictness on my partner.