It really depends on the concentration in a product, along with how sensitive your skin is.
For example, you can use a face wash that incorporates lactic acid (like OTIS Daily Face Wash) once or twice a day, even if you have sensitive skin.
But for serums or toners with a higher concentration, it’s best to start slowly. Stick to a protocol of 3 days on/4 days off, and always use it as part of your night time routine.