How long does CI take? That's a good question, particularly if you split continuous improvement into two parts; the thinking part and the doing part. If you have this clear distinction and you are short on time then fifteen minutes of CI thinking can take you a long way on its own.
I know when some of my clients are getting bogged down with their day-to-day work that even just a few minutes of thinking and decision making still moves them forward. They don't ever 'lose a week' by adopting this basic strategy.