Some recipes actually call for at least overnight refrigeration, it allows the flour to fully hydrate and improves flavor. If I'm not going to use the dough within three days, I generally freeze the dough (you can cut out shapes and then freeze, or with choc chip cookies I scoop out balls of dough, freeze them on a cookie sheet for an hour, and then keep them in a ziplock in the freezer until needed.

I've left cookie dough for almost a week in the fridge, it's fine

No it will be fine. Just make sure it's wrapped tight, so it doesn't dry out .

I need to make roll out cookies tomorrow. Can I make the dough tonight and refrigerate it overnight? In other words, is it possible to leave the dough in the refrigerator for too long?