If there is a question I get asked most frequently it is "When you sharpen my knife how long will it last?" This is a tough one because there are a few variables and that makes it sound like I am avoiding the question.
The first and largest factor is the steel recipe used when the knife was created. There are literally hundreds and hundreds of possible combinations of elements that a manufacturer can choose from and is impossible to tell anything from just looking at the knife. For this reason, before you purchase a knife, it is imperative that you are familiar with the name and reputation of the manufacturer. But since the customer is usually asking about a knife they already own this point is moot.
The next variable addresses the frequency of use. Most folks say they use their knives four or five times a week.
The type of cutting board is the next factor and there is none kinder to the cutting edge of a knife than wood. There are basically two different views on cutting boards: wood versus plastic. Those favoring plastic will concede that it is harder on knives than wood but, more importantly, it can be put through a dishwasher. The way I see it, since you should be hand washing a knife with warm soapy water after every use anyway, why not wash off the wooden cutting board at the same time.
Finally, there is the frequency of steeling. Whether you choose to steal your knife before or after you use it makes no difference. The fact that you steel your knife every time you use it is the single biggest factor you control in the equation. And the best time to start and continue this new habit is immediately after a sharpening.
So the answer to the question is...
Probably 3 or 4 times a year. This might seem like a lot more often than you are accustomed to but once you experience a sharp knife you will immediately develop a very low tolerance for dull knives. Most folks have tolerated dull knives for so long that they can't even remember what a pleasure it is to prepare a meal with sharp cutlery. Please come by and treat yourself to a sharp knife soon!