Servers/wait staff, do you find it rude if patrons stack their plates while waiting for the check?

Not at all! I used to wait tables, and I always appreciated it when people did that. It shows that they care about helping to clear the table and make the process smoother for the staff. It also gives us a little head start when we come to clear the dishes. Of course, it’s important not to stack them too high or in a way that makes it hard to carry, but a little effort to tidy up is always appreciated!