If you have gone through the hassle of finding high page rank (pr5+) URLs on .edu blogs, have the brainpower to leave a decent comment so it does not get removed. 
Many of them have CAPTCHA, so I know you are making comments manually. Why not save the mindless spam on sites that are much easier to find? A PR6 .edu URL that is also auto-approve is not easy to find, so why not take a few seconds to read and leave a comment instead of spamming the same link 3 times in 3 comments with no other words?
This boggles my mind.
Many of them have CAPTCHA, so I know you are making comments manually. Why not save the mindless spam on sites that are much easier to find? A PR6 .edu URL that is also auto-approve is not easy to find, so why not take a few seconds to read and leave a comment instead of spamming the same link 3 times in 3 comments with no other words?
This boggles my mind.