It is a bit marmite - it is, as everyone says, different every day, and unpredictable.
Some people don't like that. They don't like being constantly interrupted. They don't like the fact it is difficult to ever concentrate on a task until it is finished. They don't like the fact they end up doing all sorts of other jobs that many would consider outside the remit of an administrator.
OTOH, that is all part of what makes the role so wonderful for other people. The variety, the interactions, the interest and the difference you can make.
Schools generally don't have a culture of people leaving when something urgent comes up. Presumably you would be paying for childcare anyway, so where there is an emergency they would deal with it.