Do you re-read through the common route between each side route?

[Fred the Barber]

The way I usually go about common routes (in your average five heroine vn) is I will play through the first one, skip the second time, try and fail to read through the third time, skip the fourth and finally, wait a while before doing the final route then read all the way through that. 

[Thunderbro]

Nope, I only read the parts that I haven't read before. 

[Shoon-kami]

I'll replay any scenes I found entertaining, but other than that, skip.

[Clephas]

I should say that this is yet another area in which my well-trained story-lover's brain doesn't work the way the average reader's does.  When I'm reading a story, I have no difficulty keeping track of everything that is happening, which characters are which, how they react, etc. etc.  Compared to reading Steven Erikson's Malazan Book of the Fallen, even the most complex VN story and cast of characters is as simple to remember as what I ate for breakfast.