For reference, MIT has two undergrad courses - 6.006 and 6.046 - which use CLRS, covering about half the book each. An undergrad course at MIT is expected to take up about 140 hours, including lectures, reading, and assignments. So, working for 10 hours per day, one could theoretically complete each course in two weeks.
There are a few other things to consider. One is that it's probably not necessary to go through all of the material to be able to manage interview-type questions. (It would obviously be best to undertand CLRS from cover to cover for the purpose of becoming a better engineer, but that's not what's under discussion.)
Second, it's really questionable whether someone can effectively work for 10 hours per day on this sort of material. My guess is that people fall into two categories - those who are not used to algorithmic thinking, and those who are. People from the first category would not be able to absorb that much new information that quickly, so for them, what I said is inaccurate. However, people in the second category would not only be able to process CLRS in large batches, but would need much less than 140 hours to work through half the book; someone familiar with the underlying concepts (basic programming, probability, etc.) and with a background in proofwriting could very well get through enough information to answer interview questions twice as fast or faster, so in about a week or less.
I don't doubt your claims about the amount of the work the two courses at MIT require. However, you're forgetting that for some of those 140 hours you're being lectured by the top professors in the area. You're unlikely to have a question that they can't answer. Other parts of those 140 hours are spent talking with some of the smartest students on the planet. Some more of those 140 hours are spent solving problems carefully designed to maximize understanding. If you can't figure something out, you have fellow students, TAs and professors to harass. Somebody studying alone at home doesn't have this environment.
And then you need to take into account the fact that if you're undergrad at MIT you're already smarter than 95% or so of the population. Basically, the takeaway here is that your 70/140 hour number applies to something like 0.1% of the population under the assumption that they're studying CLRS at home.
You need to see this in context. This is advice for CS undergrads looking for jobs. This advice is being given out on reddit. Anybody who needs this advice (and CS undergrads from MIT certainly don't) will not be able to work through CLRS in a week.
There are a few other things to consider. One is that it's probably not necessary to go through all of the material to be able to manage interview-type questions. (It would obviously be best to undertand CLRS from cover to cover for the purpose of becoming a better engineer, but that's not what's under discussion.)
Second, it's really questionable whether someone can effectively work for 10 hours per day on this sort of material. My guess is that people fall into two categories - those who are not used to algorithmic thinking, and those who are. People from the first category would not be able to absorb that much new information that quickly, so for them, what I said is inaccurate. However, people in the second category would not only be able to process CLRS in large batches, but would need much less than 140 hours to work through half the book; someone familiar with the underlying concepts (basic programming, probability, etc.) and with a background in proofwriting could very well get through enough information to answer interview questions twice as fast or faster, so in about a week or less.