Dropdowns have this neat feature where you can press a key on your keyboard when they have focus to jump to different options. Consider the following example:
Here I have a Part selected with Brick as the material. In the property window the Material dropdown has focus. Now if I press C, the cursor will select Cobblestone automatically; If I press C again it will select Concrete. Super neat! This should speed up my workflow in theory, but in practice it does not. If I quickly press C twice, the cursor will still be stuck on the Cobblestone option. This is because there is a cooldown of half a second after every key press, which resets after every input. So if I spam the C key, nothing will happen after the first selection change.
These cooldowns are annoying and counterproductive: Keyboard shortcuts are meant to speed up workflows, but adding cooldowns to them defeats that purpose. In my book it is best for them to be removed as there is no benefit in having them.
tl;dr
If I want to spam a key on my keyboard to quickly navigate through dropdown options, let me do that please.