Found myself stuck behind an IB A320 after landing on 15R in MAD around midnight recently.
If you taxi that speed on your last arrival at night most airlines won't care. It doesn't affect they're on-time performance as it's your departure time that counts. At midnight it can be assumed there won't be a turnaround...so you won't be delaying the next flight.
The only sense I could see in doing this at around midnight is delaying time with your family and friends etc? Not clever