Use the novus stuff with good results. I ride many miles and have to even replace the shield every couple years, I would have to replace much sooner without the scratch remover/polish products.
Yep, windshields seem to naturally require replacement every few years. This is particularly true if you haven't cared for them. Several years ago, I scratched a portion of a detachable windshield. I learned to live with the scratch until I replaced the windshield. I also learned to be more careful when I removed a detachable windshield!