The real question is how many quality link requests you get in a day. If you are looking for a traffic partner, you will be lucky to see 1 every month that can give you any traffic. You really have to form a true business relationship with the highest quality sites to see traffic benefits.
For backlinking purposes it seems that 2 out of 10 seem to be worthy enough. There are a ton of automated link requests that make no sense, someone just fishing for any type of link, probably a black-hatter. Then there are the slew of 3-way link requests that are written by someone with english as a second language. They seemed real at first, but after a few a day all with similar subject lines and written mostly the same, and all wanting to give you a link from the same looking website with a new domain, you quickly realize it isn’t quality. Those go straight into the trash.
Then there are the link requests that don’t give you the link you are asking for on your site. It’s like they have an automated program that picked up an old link or link from a site somewhere and are trying to automatically link their new site. If you aren’t a real person that can read our page on how to link to us, then we aren’t so interested.
We will link with other sites as long as they are real sites that real people are marketing. As you can see, it becomes pretty easy to decifer who is real and who is not. Sites must be gambling related and be in the Google index, and we check regularly to make sure they don’t become banned sites. Every once in awhile we find one. You can hurt your own rankings if you pick the wrong link partners.