I have always stayed at least 1 day on international trips until this past week. I did a 3 hour turn around at LGW since my planned weekend to London was interrupted and compressed by the snow last weekend. I explained to the immigration officer what happened and that I needed the miles by the end of the year. He laughed and said he hoped it was worth it. Then said, "well, dont want to hold you up any longer, you dont have a lot of time here after all. Enjoy your visit"
My only immediate turnaround on a domestic run has been recent also, At JFK on United I was asking at the RCC about boarding passes on the return. The person at the desk was looking rather strangely at her screen as she was looking. I told her I needed a few thousand miles to requalify for 1K. She said, "oh yes, its that time of year again isnt it." Seemed to not be too surprised.