It shouldn't take 10 lines an hour should it? I don't have experience reviewing professional code of this size, so please correct me if my assumption is wrong, but that number doesn't seem right.
As part of a quality control team, I personally went through over 1.2 million lines of working code (i.e. not including comments) over the span of about 8 months, M-F, 9am-5pm.
It really isn't. Most of the code is probably going to be uninteresting and you can do 10 lines a minute or more. Some of the code will be more relevant and might take a day for 10 lines. This would just be checking for accuracy though so you could probably just ignore a huge chunk of it.
"With enough eyeballs, all bugs are shallow^h^h^h^h^h^h buried in the critical open source dependancy underpinning the entire internet maintained by that one guy who's holding down a day job and doing it in his spare time." -- with apologies to Linus
So, yeah - this number is bunk.