1. A reply on a thread more than 2-3 days old. Usually one day or 2 isn't much because it's inactive. 2. If it's dead and reject, don't beat a dead horse. Unless you have a really good automatic accepting point, then no. Just leave it and don't bother making another thread if the current technology hasn't been made. 3. Even if it's not rejected or replied to end it, don't reply to it or ask a question. Open a new thread if there was no conclusion (Of course follow suggestion etiquette). Also if you need to ask them some, use "Conversations" to message them. No matter what, don't reply to a thread without closure. Simply make a new one.