For any given substance, the heat capacity of a body is directly proportional to the amount of substance it contains (measured in terms of mass or moles or volume). Doubling the amount of substance in a body doubles its heat capacity, etc.
Conventional soft contacts can last up to a year; conventional rigid gas permeable (RGP) contact lenses can last even longer. Frequent or planned replacement contact lenses last one to several months. Disposable contacts last from one day (daily wear) to up to two weeks (extended wear).
To a certain extent, this depends on the characteristics of your eyes. Your optician will be able to discuss with you what is best in your individual case, but as a general point, it's recommended that you wear your contact lenses for a maximum of 10-12 hours per day. Wearing your lenses for longer may cause your eyes to become uncomfortable, red and prone to infection.