Double Playback in Review/Editing

Many video editing programs have the ability to playback at 1.5x, 2x, 2.5x, 3x speed during the editing. Usually done with the J, K, L keys.

J playback backwards, press again, playback backwards faster
K pause
L playback regular speed, press again, playback forward faster

This would be incredibly useful to be able to "review" the recording faster without having to watch the whole thing at regular speed.