Well I've used it with one days growth, two, three and finally four days growth. With a thinner lather (l'm using the Gillette official foam for this razor) and I can easily say it shaves as well with fours days growth as it does with one days growth. This cart has a 10 days on it so in my test only four shaves but its is smooth and easy as when it came out of the wrapper. one thing was on the 4 days growth I did have a lot more touch ups but still no irritation or problems.