It depends on the pattern that I'm doing. If it's the same fabric throughout, then I make some and put a row or two together. If it's scrapy, I may make all the blocks first, so that when I do put it together, I can pick and choose where I put certain fabrics or colors.
If it's a big quilt, I do the make some blocks, then put a row together thing. I guess it's my ADHD talking.