How to handle the "else" intents

Hi Rasa Devs,

Problem: We are building the stories where there are several instances where the bot asks an open-ended question and conversation flow goes to different responses/flows based on user input we have accounted for but for everything else, it should go to a different response and this response is different in each instance.

Current Approach: Since we cannot anticipate what users might say other than the expected input, I am using a bunch of OR statements with a long list of intents which is first not working as users come up with new responses, second blows up trackers, and training time is around 4-5 hrs.