They often don't run it outdoors when there's no crowd early in the morning or late in the evening. Generally, if they only run 1 or 2 trams, no outdoors. 3 or 4 trams then outdoors is included. Thunder and lightening, no outdoors. Before the outdoors was reworked, that's how it ran according to the Kong TM's I spoke to over the years. So generally, I avoided early mornings with short lines since the attraction is vastly better with the outdoor section.