I hate waiting for responses. It isn’t necessarily that I’m impatient. I can hang in there pretty well.
It’s just that once I know the usual response time has ended, I wonder what to do. Is it time to query? Should I wait another day? Another week? It isn’t so bad if I can send a friendly email to the editor, but sending through the post office? What if the original didn’t get there? (I know, send a self-addressed stamped postcard and get a response as soon as it’s there.)
If a response isn’t given in the time generally allotted, some markets just aren’t interested. Sometimes it’s difficult to know which is which.