Slight off topic, but I am always puzzled how most conference rooms fail to have a large clock at the back of the room such that a speaker can easily see how they are tracking for time.

If not at the back of the room, a large display at the foot of the stage facing the speaker - the way TED talks display the time to the speaker.

If meeting rooms can remember to embed projectors and speakers in a room, putting a clock on the back wall can't be that difficult.