Angel
Not only beneficial but sometimes crucial! I once did a big adwords campaign for a client of mine and had 25 different landing pages. After examining them closer, I found out that my landing pages were more descriptive and had better content and longer visitor time on site than the client’s actual pages.
What we did was to incorporate the landing pages on the menu, helping visitors find what they need and helping the client, rank for all his main keywords.
Try it, you never know :)