The mechanics of the leap itself required more time.

Indeed, it took the better part of a morning to satisfy Baird that this thrilling exploit had been properly achieved.
From a lower window, quite like the high one, Merton leaped, but only to the ground a few feet below.
"That's where we get your take-off," Baird explained.
"Now we get you lighting in the saddle." This proved to be a more delicate bit of work.

From a platform built out just above the faithful horse Merton precariously scrambled down into the saddle.

He glanced anxiously at Baird, fearing he had not alighted properly after the supposed twenty-foot drop, but the manager appeared to be delighted with his prowess after the one rehearsal, and the scene was shot.
"It's all jake," Baird assured him.

"Don't feel worried.