One would have a cached answer to a problem if the circumstances and question were identical, i.e. same function, same input. In normal conversation, these are almost never the same. In addition, language is faulty and ambiguous. As an astute reader, one has the responsibility to attempt to understand the argument in the full complexity of how it was meant, not just how it was said. To this end, there are very few identical answers to identical questions. Certain answers may be similar to answers given to similar questions in the past, but they should never be knee-jerk. Instead, they should be reasoned and polite with as much understanding as possible. Of course, everyone responds out of frustration at times, but this should never be held to be ideal.