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).
I wear disposable contacts as well, 2 week contacts. I usually wear them for a month though, and I wondered if it was damaging to my eyes. I asked my eye doctor about it, and she said that as long as I clean them every day they should be ok.