I have a review site and im using wordpress pretty link plugin.All my links are directing to the same vendor url.Do you think i should vary the affiliate urls?is it necessary?
Are you asking if you should change the affiliate links to point to different vendors?
If so, you should only do that for:
1. Testing purposes to see which vendor performs the best.
2. Websites promoting multiple products.
If you already have a product that's selling well or if your site is targeting one product only, you would be better off sticking with it.