I've often wished that every time an engineer created a new Pro Tools session that a big window popped-up and asked "Plug-In Controls Default to Auto-Enabled?" This preference box is unchecked by default, but is absolutely essential for modern mixing workflows.

Let's imagine Al is mixing dialog, with maybe an EQ, de-esser and compressor in the chain, and then he gives me the session. I keep mixing, but then I notice that the de-esser threshold is too high for one line, but everything before it sounds fine. If I pull the threshold down, it will affect everything before it, so it must be automated. But just looking at the plug-in, I have no way of knowing whether or not the threshold parameter has been auto-enabled!

To keep from going insane, I auto-enable absolutely everything in a session, but start a mix in auto-suspend mode. In auto-suspend, you can tweak, fiddle and play for hours, and then when it starts to sound good, use write-to-all-enabled for all tracks and turn off auto-suspend. This will lock your mix in, and give you the freedom to make moment-to-moment tweaks.