How many related columns should you use on a model. Does it matter?

[Ry]

How many related columns should you use on a model. Does it matter?

For example, say in a payroll application I have a model Company. Each Company has multiple model Employee. Each Employee has a Job. Does it matter if the final model, Job has a fk to both the Employee and Company model or should the Job only have a relation to the Employee model?  

What is the school of thought on this and why?

Thank you.

[Ryan Nowakowski]

There are many academic and practical considerations. I'd start here:

https://en.m.wikipedia.org/wiki/Third_normal_form