Whoever had planned the patrol routes was clever enough to have them so that there was always at least two pairs patrolling the garden at all times, and even without those there were plenty more watching from a distance. Yes you could hide in the bushes, but how long you could do that for without getting spotted was debatable. Twilight was starting to think that if she wasn't trying to divert a serious diplomatic incident by being a princess, she'd simply do this the hard way and attack directly.