A disposable razor is usually for one-time use or limited use. The general rule is that they can last three to ten shaves. When the blade goes dull, that typically means that it is time to change the blade. High-quality disposable razors will stay sharp for multiple shaves. Some factors can affect the razor's life which includes:
Thick body hair
Excessive moisture left on the razor
Shaving against the hair growth, which causes the blade to wear down faster
Not cleaning the blade, which causes corrosion