Dynamically adding templates

I am using autoform, simple schema, and collection2 two and would like to know would it be a problem if i am building a workout app where I would like to add an unknown number of exercises to a workout. Do I need to define something in simple schema to handle an unknown number of collection fields since I don’t really know exactly how many exercises may be added. Do I need to switch my forms to not use auto form or is there a way to do it? If i need to switch away from auto form what would I need to use in order to validate the form on the server.