Wind Dragon Math! (because we all love math!)
Cloud drake!
It was recently brought up in another thread I made that cloud drakes might be useful. Lets investigate:
To move the sidelane you need to cross about 8100 units. To move to midlane you need around 6500 units.
First, lets assume the most favourable scenario: You have 325 base movement speed. With the wind Dragon you have 340 movement speed.
Therefore it takes 20 seconds for midlane and 25 for sidelane. This means a single wind dragon saves you 0.89 of a second when you move to the midlane and 1.1 of a second moving to the sidelane.
A normal scenario: You have 340 movement speed, 45 from boots. You also have an item that increases your movement speed by 5%. Without dragon: 404 movement speed. 16 seconds to get to midlane. 20 seconds to get to sidelane. With the dragon: 420 movement speed. 15.5 seconds to get to midlane. 19.3 seconds to get to sidelane.
You are considered "out of combat" if you did not deal or receive damage in the last 5 seconds. The wind dragon is useless when splitpushing since you are in combat with minions and for junglers since you are in combat with the camps - the out of combat buff doesn't kick in before you start another camp.
Conclusion: The wind dragon saves you between 0.5 and 1.1 of a second each time you move to lane. It's useless in nearly every other scenario.