If you can fully understand it in two days, by all means do it!!! But do not rush learning if it means you take a few days more to understand all the concepts!!! Your only going to remember/memorize 5% of the material! But the concepts you learn stay for much longer and are a whole lot easier to remember.
I totally aggre with you. If you thoroughly understand and read something , even if u read it once . It is more useful . The mistake I did when I read everything first time, Which was superficial and now I understand I have to do go little bit thorough .