Place a 5 second image at the start of the timeline and open the Size/Position dialog.
Press the Home key. The marker moves to the start if it wasn't there already and the time indicator (top left) shows 00:00.
Press the End key. The marker moves close to the end, but not fully. The time indicator shows 04:23. Two frames left of the RH edge.
Instead of using the End key, click anywhere in the keyframer timeline and slide the marker as far right as possible. The time indicator now shows the correct reading, 04:24.
This doesn't make much practical difference to me, except for presenting another problem to be solved when I'm trying to write macro scripts for KF work. But for professionals requiring animation precision I imagine it might do. It might also explain the single frame quirks I sometimes get at the end of some zooms and pans.
Presumably it's a minor bug, as I can't think of any design reason for the inconsistency?