I forgot to say that I squared all the blocks up to 8" to finish @ 7.5". I make the scrappies long enough for people who are over 6' tall as they usually go to charity.
Also, for the wide end to be in the center, cut the squares face down. Conversely, if you want the narrow end of the blade in the center, cut the squares face up.
As for using the 3" precut strips, I have no idea how it will look when it's finished because I'm cutting one pair at a time and not planning ahead on how I want it to look so that's why I laughed out loud at the one really wonky block! You'll be amazed at what you end up with!!