If all of your needles are pointing to green, and nothing is blinking red, your flight is probably going pretty well. Quick-glance color coding can be just as useful on your calendar.
Some people use colors to categorize things like "personal," "work," "kids," etc., but assuming these are all things that you need to focus on at any given time, I'd argue that this approach may not be giving you as much value as it could.
I prefer to color code based on how time sensitive a given task is. Lighter shades indicate that this task can happen at any time, whereas darker shades are for things that can't move. This way, I can see how much "stuff" I have on a given day, while also maintaining some agility to shift things quickly to accommodate other meetings, without overloading my day -- or my mind.
