I have done both. Doing it in block sections makes it easier to keep track of what block goes where. But I seem to get a btter looking quilt with better matching seams if I do it in rows. And as mentioned earlier, when doing it in blocks, pay close attention to which way you press seams.

I like working in rows - that way I can make changes if I want to a little easier. And, I make sure to sew the rows in opposite directions (start sewing rows 1&2 at the first left edge block of both rows, then sew row 3 on to row two beginning at the right hand edge of each row.

I, like the scissor queen, assemble my squares into blocks and then into 1/4 of the quilt. My design wall is not real big and my sewing room is small so it is just much easier to work in smaller sections.