Hi, I find there is less waste and it is easier to keep the yarn in tact. But I change the color at the end or begin of row when possible, in this case you will be joining at the end. The only exception is if you are working a lot of rows you don't want a big loop on the side. When or if you ever weave besure to leave a long enough strand for weaving. I always weave one way then reverse directions and weave some more. It is less likely to come undone and stick out.