Yeah. I get that this would be nice information to have. Basically, the gig form has the commonly used time attributes, as you have seen. When can we load in? When is sound check? And what's the gig start,end. time? In some situations, we need more detailed information, like when we need to vacate the room.
For this sort of information, we can use the "Info for band members" field on the "Info" tab of the gig form. The information you add there (supports complex formatting, also) will be printed on the gig detail page, and in the gig alert and gig reminder emails.