How to subset common datetimes from multiple timetables

I have five timetables which contain data for five locations across a common time period. I have presented these in a histogram here, binned by day:

As you can see, there are datetimes when there is data at all sites, and dates where data is missing. I would like to extract across all sites, only the datetimes where there is data at all site. This is count data and I would like to do this without using retime, as I want to keep the days where there was data collected, but no counts reported.