1. The Plate - If you have ever worked in a kitchen, you know that the pastry department in most cases gets the last pick of plates. Luckily, where I currently work, there is enough everything to share, although it may be a challenge to get the plates returned to you. As I mentioned earlier, we found this "doughnut" plate in storage and when I saw it, I just knew this dessert would look great on it. Sometimes however, it might just happen with a plate that's been pushed aside and ignored or even a plate you never imagined it on.
2. The Rush - There are times when you are in a rush to change something on the menu - a particular ingredient is no longer in season or no longer available. You may have the flavors of all the components to your liking, but did not have adequate time to experiment with plating. Eventually #3 will take care of that.
3. Repetition & Comfort - It honestly takes a while to become comfortable with the components of a dessert and plating it. Even if you don't change anything in it's plating, your 100th plate will look immensely better than your 1st. As you are constructing plate after plate, you start to realize what works and what doesn't. The final product gets the last little tweaks it needs here.
4. Recognition Memory - After you've been at it for awhile, you will realize that plating is an art form. Soon enough a plate will become second nature to you - everything will fall into place every time. The look of your plate will look effortlessly beautiful and natural as if everything was meant to me exactly where it is.
***These are just my thoughts, if you you can think of any other factors, let me know!