Have you observed your most productive day? What did it encompass? Can you fully re-live it every day or on most days?
Or are there parts of what worked well you can replicate?
The reality is that many people do not know which has been one of their most productive days. Some who do know have not closely observed what it is about the day that has made it the most productive day. This lack of examination makes such days difficult to replicate.
Imagine you knew what is it that made your day the most productive day? You can use the results of your observation to intelligently design more days like these, or at least replicate parts of them on a daily basis. This could significantly enhance your productivity!
By the way, your most productive day is the day before your holiday! You have a sense of urgency, a tempo, a spring in your step and you make decisions promptly!