I haven't been tracking PLE by node before now, but the max I've seen for the buffer manager counter is plenty high: 50,000.

If I graph the this counter over the last week I see a dozen-and-a-half or so precipitous drops from very high values (20,000+) down to virtually zero. There's no obvious pattern to the timing, even if I round to the nearest hour. Sometimes it's at around 4 am (start of ETL's), but it also can occur at seemingly any time day or night.