Current job an Opportunity Cost

Continuing with one's current job is an opportunity cost if you will. My questions is how does one decide its time to look for a new job/opportunity? Are there any thumb rules to this?

This question was asked and shows the person is thinking and on the ball.

What many chase is the comfort of a job that is hidden in a closet, that they hope will last forever and leads nowhere.

This would be good for them if there theory worked but shakeups happen and all those cosy dark 'cost centres' will be the first to experience the light.

Aside from that these jobs will NOT suit the person that wants to use their career as a powerful way of expressing more of who they are but can spend time ineffectively, in a stepping stone position, longer than they have to

BECAUSE they are not aware of the OPPORTUNITY COST there current job is.