Yes i understand those issues quite well. Special order materials are the worst I face. One fancy part holding up weeks of schedule kills me.
We're getting better about planning things out earlier though and I use a project management software now that keeps suppliers and subs all in the intended loop. It makes the problem black and white as to who or what the hold ups are. Instead of "Smallie sucks" and lack of engagement, it goes like "oh man he is keeping a record" we better stay on point.