Vol 1 may have said that years ago, but the 2 hour limit is removed now. Also, the secure checklist does not say to pull the CBs. It's only the Shutdown checklist that mentions the CBs.

The way it was explained to me years ago on the 717 was you either pull the CBs or do the Secure checklist, not both. The point of pulling the CBs is a half-ass way to allow the cabin to remain powered. That way if the GPU fails during a turn, the battery won't be depleted since we pulled the CBs. If you are going to secure the aircraft, then there is no point of pulling the CBs.

But even the logic of pulling the CBs because we don't trust the GPU doesn't make sense. MX will power up a widebody hours before the crew gets there. Some out stations even have MX come by early in the morning to power up the plane. If MX trusts the GPU in SYR at 4am, then I think we can trust the GPU in the middle of the day at MCO.