The first time we (Chris) left the lights on was when we went to get groceries from Tesco. No problem.

The second time we went on a 4 hour walk through Welsh countryside. Fortunately we managed to find somebody with jump leads. I imagine a callout to the middle of nowhere on a bank holiday weekend could be expensive.

Lessons learned include possibly having a checklist like pilots and surgeons to prevent this sort of thing from happening in future.

Included would be things like keys, lights, going through the checklist.