Limit the amount of staff assistant slots if the pop is too low

[Angel]

An issue that often happens on lower pop is the station being understaffed, lacking doctors to heal people or engineers to fix things. Yet, sometimes in low pop classic shifts, you will have 0 engineers, 0 doctors, and sometimes even 0 command, but like 5 staff assistants. My suggestion is to limit how many staff assistants you can have at lower pops to try and get people to play roles that supports the station more, instead of picking staffie and just greytiding their way into places.