MTS

S to S = WOF

Bias bindings are really only needed on edges that have curves (scallops,etc), or if you want to take advantage of the fabric design (stripes, etc).
Otherwise, cutting the binding strips WOF and joining them works just fine.

I usually don't use sashings, or if I do, there are cornerstones or something else breaking them up, so I can easily cut WOF.

I don't really worry that much about stretch in the sashings.
Actually, I've never even thought about it.

However, it would depend on the fabric pattern to determine if I would cut LOF or WOF.
If it's a relatively solid fabric, then joining together on the diagonal (the same you do for binding strips) and pressing well, will result in an almost invisible seam.

If, however, there is a busy pattern that I don't want to disrupt, then I would cut it LOF.

But keep in mind that you have to be careful, as sometimes the same fabric cut LOF and WOF can look totally different in the vertical and horizontal sashings.

And that's TOTALLY up to you and your personal aesthetic to decide which look you prefer - LOF, WOF or a combo.

eta: also if I had a long sashing on the outside, regardless of how the strips were cut, I would most likely be joining that to the other BORDER strips, and then adding them all as one to the quilt center.

As I prefer the look of mitered borders, it's much easier and cleaner to line them up this way.