Normal use on the one side ( manuafacture) is whatever they will stand behind. Which in SY terms is pretty much anything. On the other hand- what the consumer expects can sometimes border on " ridiculous" . This is also how a manufacture builds his name and his product line. In Bussekin- this is also what makes their demand so extreme. In other words- it is a terific VALUE. As for other blades- I simply don't know at this point as I am only buying Bussekin. Thanks