I have seen center blocks a little larger or the same width of you cut strips so it would depend on what size you want your blocks to be.
https://www.google.com/search?q=log+...w=1013&bih=600
If when you sew your seams, if you find you are a tinny bit short, I always cut my final outside strip an 1/8" of an inch wider and then was able to trim down the blocks perfect so they all were the same size.