I figure my material needs out before hand. I make a little sketch of the design just to make sure I've got all the fabric requirement correct. I buy the fabric and usually add 1/2 yd/m extra. I then cut enough to do the first block, starch, sew, iron and see how it looks. I like instant feedback and I can also make any changes before cutting all my material. Most of the time my pattern and material look great and I continue, 1 block at a time. I have had to occasionally switch out the placement or even a material if the block doesn't look like I want it to. Starching, ironing and cutting all the material would bore me and my sholder/elbow can't take doing all the rotary cutting at once anymore.