The anticipation effect
Have you ever felt like part of the joy of pencilling things you enjoy in your calendar is in the anticipation of said thing?
That's something I've certainly felt during holiday planning. For instance, my family has been planning a holiday for a few months and tomorrow's the day! Having had the holiday on my calendar gave me something to look forward to during an intense period at work, which made things just a bit easier!
I think spontaneity is definitely valuable in our days. But a case can definitely be made for adding things you enjoy to your calendar ahead of time, and reaping the dividends of anticipation.