That's true, but I doubt we'll get to know if they are about to lose their job. This could always be the situation. As landlords we face an element of risk and exposure every time we take on a new tenant, there are never any guarantees, I've had the best tenants (on paper) doctors on good pay who went into arrears for no good reason then disappeared leaving 6 months of arrears.
I go into this business with my eyes wide open and a healthy contingency 🙂