As far as I understand, you suggest creating banners with dimensions: height - 50 pixels, width - 150 pixels?
No, 50x150 is very small for a regular PC screen.
I think about automated size ads. So, an ad from the same place can be in various sizes, depending on the user's screen display. I use a similar thing when I place ads from Google Adsense. In this way, I always get a proportionate banner and all with the same code.