When were Vaults supposed to open.

[VikVega]

I understand that certain vaults had to be sealed for a certain number of years such as Vault 3 and 8 which were meant to open after 20 years and 10 years respectively. But my question arises in the cases of Vaults like number 15 which was meant to be closed for fifty years, but was open in 2141, 6 years short of that goal. Or in the case of Vault 13 which was meant to be opened after 200 years but was opened and closed several times before that time had passed. Vault 11 was closed until the dwellers chose to defy instructions and not sacrifice a fellow dweller.
Does the overseer have the power to open the vaults whenever they please?
Does the required time have to pass in order to open the door, or in the case of Vault 11, after experiment criteria is met (choosing not to sacrifice a dweller)?
Or is this just a minor detail overlooked by the creators of the series?

 

[durstlimpbizkit]

I don't think it was overlooked by the creators necessarily, but my thought process was always that some of the vaults were opened because of people defying orders. Glitches, literal issues with the technology contributed to some of them opening early. As far as the control the overseers had, I would think they have a little more control over the entry and sealing of the vaults; if that weren't true then fallout 3 never would have happened.