Stepped Playback (Bookmarks Only)
Stepped playback allows animators to playback only bookmarked frames, holding each image until a new bookmark is reached. It creates an effect similar to switching your animation curves to stepped mode in Maya’s graph editor.
To begin playback in stepped mode, hold down the Ctrl key (Windows) or Option key (macOS) and press the Space bar or play button. The fps label on the main timeline will display "Step" during stepped playback.
When stepped playback is started, or when a seek occurs during stepped playback, the playback time will jump to the bookmark for the image that should currently be displayed.
Note: For stepped playback, at least one bookmark must exist in the current playback range.