Never "go for the long one" at any jump into water that involves height. If you do, one of 2 things are likely to happen:
1. The horse will (quite rightly) ignore you and add a stride.
2. The horse will listen to you and take off early, but will probably hit his stifles hard on the fence on the way down.
In the sport of Eventing, ensuring that our horses are truly fit for our level of competition is one of the best ways to prevent unnecessary injuries.
Horses become incapable of learning when they go past a certain level of fear, anxiety, or stress. This means that if you keep hammering away at the horse, trying to teach them something when they are currently overwhelmed with stress, it will not work.
For the horse, the learning happens on the release of the aid. That means if you don't release the aid, the horse will not learn.
"Don't take the tempo down without revving the engine." ~ Chris Bartle