I'll make this real easy. IF EVERY SINGLE USER NEEDS IT, then it can go on global navigation.
Otherwise, you're wasting precious navigation space for links nobody wants.
Still really need a selection of staff to have one-click access to something? That's fine, you should look at implementing a personalised list of shortcuts on the homepage that each user can manage themselves. That way that specialised safety system they access everyday takes up their screen space and no one else's.
That brings me to : How To Set Up a Personalised Shortcuts List on a SharePoint Site
This is almost a golden rule for me, what're your thoughts?