I was invited at a conference to give a contributorycontributed talk. I was given 12 minutes to speak and 3 minutes for Q&A, but to keep my talk simple I didn't go in details (probably I spoke faster also) and. In all, I finished itthe talk in ~10 minutes. I know this somewhat disturbs the flow of the schedule, but it also gives more time for discussion.
What is the general impression in such cases? Is it bad to finish your talk early?