I had read a tip some time ago that I remembered for once (I think it was on the Moda website) and as far as possible I cut the strips for the logs down the length of the fabric. The only ones I didn't were the dark outside ones as it wasn't economical to cut them that way.
Why ???
Find a piece of (woven) fabric - a fat quarter would be ideal. Grab hold of it so that your hands are on the middle of two opposite sides, hold firmly and try to pull your hands apart. Notice how much 'give' there is. Now rotate the fabric 90° and repeat the excercise. I'll guarantee that there is more give in the crossways direction than there is in the lengthways direction. Rotate the fabric 45° and try again; you are now pulling on the bias and it will have even more give.
The reason the fabric stretches less in the lengthways/warp direction is because when it's being woven the warp threads are held under tension whereas the filler/weft threads are not.
This is the reason why garments and curtains are nearly always cut on the lengthways straight grain. I have a dress - looks better on than hanging - which being a border fabric I cut it all in the cross direction. When I put it on and smooth the skirt down I can actually feel it stretching.
With patchwork it doesn't matter which way small squares and triangles go, and you probably have the bits all muddled up and going in all directions, but when it comes to borders you do get more stability if you cut the fabric lengthways.