Pay Raise vs. Hiring New Staff

I only just started playing recently. (On the Android)

Everything I have heard from long time players is to NEVER give pay raises to attempt to increase productivity.

This will only lead to huge expenditures across all staff categories and eventually bankrupt you. (according 1 source)

I have been told to try and keep the efficiency level at or above 70%. And when it starts going lower than that, hire another employee for the category that is in need.

I have yet to try this but I makes sense.

My suggestion (and I don't know if t will work) would be to fire ALL employees in a category and hire an entire new staff. *example- Fire 4 captains, hire 4 captains*

I do not know if they game will even allow this. Can you have less employees than you have vessels per category, if only 1 employee is required (such as Captain)

Maybe the ships will have to be in port to do this?