Back in the Days of regional television, not only did you see plenty of station logos but the station clock was often cut up to air, it was distinctive and reflected the stations identity. Only an occasional event now. Possibly one reason might be, with the advent of digital transmission there is a significant delay between the playout centre and the viewer, rendering the visual time check inaccurate.
Here's a selection of recreation TV Station Clocks, if you click on the clock another window will open showing a live clock.... telling the correct time!
These clocks are from 'Andrew Wiseman's Television Room' and are the work of Dave Jeffery.
I would encourage you to visit his site, it's a great resource. Link details at the bottom of the page.
For more files from the Golden age of Television please visit 'Andrew Wiseman's Television Room' Here there are features, articles, logos and much more.