Management seem to think it's OK for a Supervisor to book on at Canons Park at 06:45 but not do a station check until after 10:30. So staff and passengers will be left trusting to luck that the station is safe for those four hours around the morning peak.
Why are local management doing this? Because they are determined that the ticket office should open at 07:00 on the nose, even though this is one of the ticket offices the company was trying to close last year!
Managers are helped in their endeavours by the new Rule Book (more of a guidebook, really), which reckons that it doesn't really matter when a Supervisor checks the station so long as you have a stroll round once during your shift. So if, say, the night-turn SS did his/her check at the start of the duty and the early turn at the end, then the station could go overnight and well over 12 hours without being checked!
Tube workers continue to live with the consequences of management imposing a dangerous Rule Book and our unions failing to fight it.