Is it Ok to build more back links at very short time, say 500 external links a day? Will google ban the adsense account and the site also?
I dont think that backlinks have anything to do with adsense account. 500 links a day? Dont you think that its a little too much? Dont seen very natural. Worse that can happen is that google will ignore all those links. Some people say that you will be penalized for too many backlinks in search results. But I dont think that its true. For example, if google ban or penalize people for too many backlinks, then people will start building hundreds of links for their competitors inorder to get them banned from google.
adsense will not even know that you built some backlinks. but if you build too many backlinks in one day all of a sudden, google might put your site within sandbox and your SERP will be affected. build links slow and steady
Adsense account will not be affected but Google bots will definitely consider these backlinks as spam. Any your website will not get a credit for these backlinks.