In the USA we readily succumb to the notion that more is better -- that if one is good the five must be great. So it is with multi-blade razors. Blades of any design obviously become dull with use, eventually to be thrown away. However, it is not clear that a five-bladed razor will last as long as five single-bladed ones -- probably not. However, what is true is that when the blades of a multi-blade razor start to get dull, you are now trying to drag several dull blades across your face at the same time -- the total drag resistance is now the product of the drag of one blade multiplied by the number of blades.
The deterioration curve in such a situation is much steeper than in the case of a single blade. Due to this increased drag, you are likely to want to replace the multi-blade much earlier than you would a single blade, even though the individual blades may still have several more shaves in them. My experience tells me that you get a few spectacularly clean shaves from a new multi-blade, but that they go downhill quickly -- just what the manufacturer wants.
I am convinced this is a case of buying more but getting less for your money.
Other myths to follow.
