For uni we get assignments based on our classes. I'm always super excited about these and immediately start thinking about how I would implement it and come up with cool features I could add.
I would write out the whole thing and plan everything. Eventually I get distracted by other assignments or things. Then 1 or 2 days before the actual deadline I start coding like a madmen, thinking about al the features I wanted to implement and realizing I would never make it in time.
That's the moment I switch to plan B. Which is creating the best possible demo I can present. Most of the time this does the trick. I would show my professors the demo and they wouldn't notice the completely broken application and the code that was hacked together.
Luckily I always managed to get good grades!