Ask what would stop a small business trading tomorrow and the answers come slowly, because the dependencies are so familiar they have stopped being visible. The van. One machine. One supplier who provides a material nobody else stocks locally. One person who knows the pricing. The phone number that is on everything. A single account through which all payments arrive.
The exercise is to list them deliberately, and the prompt that works is not what is important but what would stop work this week. Not slow it - stop it. The list is usually shorter than expected and contains at least one item that surprises whoever wrote it, most often something administrative rather than physical: an account in one person's name, a piece of software holding the customer list, a certification that permits the work at all.
For each item, the question is how long recovery would take. That number matters far more than the risk of it happening, because it decides whether the event is a disruption or an ending. A van stolen overnight might be replaced by a hire the same day, which makes it an inconvenience. A specialist machine with a lead time of three months, or a licence that takes weeks to reissue, is a different category, and it is worth knowing which is which before the phone call rather than during it.
Most of the fixes are cheap when done in advance and expensive when done under pressure. Knowing a second supplier exists, and having bought from them once so the account is open. A spare of the part that always fails. A second person who can run payroll. A written note of where things are and how they are done. None of these are dramatic investments; they are mainly a matter of having thought about it, which is the part that does not happen on its own.
The reason to write it down rather than hold it in mind is that the list also tells you what not to worry about. Small businesses tend to carry a diffuse anxiety about everything going wrong at once. Replacing that with four specific items, each with a known recovery time and a decided response, is both practically better and considerably easier to live with - and it makes insurance, which is otherwise bought by guesswork, a decision based on something.