How different is a small blind call from a Button call?

[Doc7]

This may be discussed in SSHE, I'm still reading the preflop section, but...It seems like the Big Blind is always 2.5 times the small blind. Like .02 to .05, or .10 to .25. This seems like a pretty hefty amount, so does that mean that the amount of money already in the pot is almost insignificant compared to completing the full blind? Should we be that much looser from the SB as from the button (or even tighter because of horrible post-flop position)?