Nicads usually hold their charge pretty well. I've tested packs that sat for a week, and had them show 5.0v, which is a pretty fresh charge. But I've also had packs drop off over that week, just normal variance and such.

So, no, I wouldn't fly a week "stale" charge. But the good news is that I would fly a pack that was charged a week ago, then only on the charger for a few hours prior to flying. I've used a fast charger in the car, and had the plane fully charged before I reached the field many times.