Daily contact lenses are so named because they are made to be worn during the day and not overnight. While some are worn only once before being discarded, others are made to be worn for a week or longer before needing replacement.
No matter what contacts you have, the more often you change them, the healthier it is for your eyes, as frequently replacing them reduces the build up of proteins, lipids, and bacteria on your lenses. (See Reference 1)
Daily Contacts v. Daily Disposables
Daily contacts are meant to be worn for several days or weeks before being replaced, while daily disposable contacts are worn for only one day. (See Reference 1) Wearing daily disposables more than once increases the risk of complications.
Wearing daily contacts for more than the recommended amount of time increases the risk of harmful bacteria growing on your contact lenses and causing eye infections. (See References 1, 2)
Daily disposables are comfortable because you wear a fresh pair every day. (See Reference 1) If you wear them again, protein build-up blocks oxygen flow to your eye, and water content drops, causing eye irritation and dehydration. (See Reference 3)
Replacing daily contacts on time helps prevent loss of vision acuity, as dirt collects on your contact lenses over time and may cause blurry vision.