Fill up a sponge and it is nearly impossible to get it to absorb more. It is full.
Take care of the surprises you can predict, so you can absorb those you don’t see coming. Everybody has a limit. There is only so much we can deal with at once. At any given point in time, we have a limited amount of capacity.
Surprises will occur. They are inevitable. Make sure your capacity is reserved for the truly unpredictable. If you have taken care of everything you could possibly predict, you will be prepared to handle the things you can’t.