Stuck between doors

[Oggm]

Say you got a part of your bag trapped in between two doors on a tube train, and you couldn't remove your bag, what is the longest wait, in terms of number of stations, until those doors open again, and you can retrieve your bag?

For example, if you got your bag stuck on the door of a s/b Victoria line train at Finsbury Park, you would only be able to retrieve it at KXSP, as the doors at Highbury & Islington open on the other side. In this case the number of stations you would have to wait would be 2.

For this I am assuming that normal running occurs, without the train going out of service at any point, for example, you can stay on a train arriving and departing from Elephant & Castle, but you can't do the same at Heathrow T5, as trains are detrained there (I think), in that case you would score no stations, as you would need external assistance from staff.

[al]

Potentially Mile End to South Kensington?

[Oggm]

Potentially Mile End to South Kensington?

Which would score 15 stations.

[Oggm]

Earl's Court -> Uxbridge (Platform 4) -> Hillingdon. Scores 19 stations (Inc. Turnham Green)