When this strategy is on you can press spacebar to add tasks or projects quickly. You can also optionally add a button on the bottom right to add items easily without the shortcut (great for touch devices).
In the strategy settings, you can choose whether you want to see the button in the main view and also if you want to have Fast Add Buttons showing up in the dialog.
If you choose to see the button, it will appear in the bottom-right corner as shown in the following picture:
By choosing to show fast add buttons all of them will show up under the input bar making the process of adding a task quicker: