When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
If you are asking if you should apply an undercoating every year. I would have to say that I would NOT. I would only apply it when it needs it.. And IF the undercoating was applied correctly the first time it should last for a good long time....depending on the level of abuse it is subjected to.
So if you have a mile long gravel driveway and drive on it as 40 MPH...then you might need to apply the undercoating yearly due to the chips the rocks have put into it under a consistent basis.
SO...as you can see ...it can depend on factors unknown to us.