There is no definitive answer to your question.
Arguments relating only to the driver often succeed; those relating to the driver and/or others often fail. This is because every case turns on its merits and no two cases are likely to be identical. There is an added complication in that an EH argument could be made to one Bench and be successful and the identical argument could be put to a different Bench and fail.
As a result, there are no lists of things that might succeed or will probably fail. It is true that, anecdotally, hardship visited on innocent parties seems likely to be met with more sympathy than that which only the driver will have to endure. But it is only one aspect of quite a complex balancing exercise which magistrates undertake when hearing EH arguments.
A few years ago it was felt by those whose job it is to worry about such things, that too many EH arguments were succeeding. The stock advice down the pub was "Just tell 'em you'll lose your job - they won't ban you." And that wasn't too far from the truth. So the latest guidance was published to remind magistrates that the word "exceptional" went along with the "hardship".
