Tweeting is a social conversation between you, those you follow, AND those that follow you. Conversation via Twitter is not just an A and B conversation. Even while you may be speaking with only one of your followers, you are speaking IN FRONT of the rest of your followers who may not be following the individual with whom you are speaking.
Therefore, when follower A says, "I can't wait until the Sewickley Farmer's Market opens," your response should be "@user, actually the Sewickley Farmer's Market is already open. Every Saturday from 9 a.m. to 1 p.m."
If you only say "It's already open. Every Saturday from 9 a.m. to 1 p.m," anybody that is not following the other user is missing out on half of the conversation. You could be sharing valuable information that could be of use to ALL of your followers, rather than a cryptic response that is meaningless.
Translation: use descriptive responses, not:
@USER today. I'll post it later.
@USER It's already open. Every Saturday from 9 a.m. to 1 p.m
@USER That's rather interesting. I wonder if the fur is real?
@USER Good question. I'm not aware of its schedule, though. I heard it only was in TOWN NAME until 11 a.m. After deadline, I'll check.
@USER We like it, too!
@USER girls lacrosseAll of these responses could be something interesting to the people that follow you, but essentially, they end up being useless Twitter chatter that could cause your followers to begin scanning past your messages. Or, at the very least, if it is something that would be of interest to your followers, you've missed an opportunity to help others that might have the same question--or caused them to click back and try to follow the course of a conversation.
Think about how you feel when you are in the middle of a conversation and somebody takes interest in a portion of that conversation. Inevitably, that person ends up having to ask "what were you talking about," or repeating a part of the conversation. Either way, you've created an unnecessary situation by using coded or incomplete responses while talking in front of the rest of your followers.
If all the information is not fit for public consumption, use the DM. That's what it is there for.