I have to ask..... What purpose would this serve in PC? Unlike RCTW, mobile staff members don't live in headquarters buildings. Instead, they wander around the park, either as a whole or within the subset of it you've given them with a work roster.
Ride operators and shop vendors don't move at all so don't even need backstage entries to their facilities.
Janitors need to be on the same paths as peeps because that's where their work is. Peeps are confined to regular paths so that's where they puke, drop litter, and fill bins.
Same for entertainers. Their only function is to entertain peeps, and peeps are only on the regular paths. Any time they'd spend on employee-only paths is wasted salary you're paying, and they have the biggest salaries of all employees, despite being the least useful.
Guards need to be on the same paths as customers because that's where the perps are. Guards only know where perps are if they get their own eyes on them, so if guards were off on their own path, they wouldn't see any perps.
Mechanics are also better off using regular paths. If you've done it right and created work rosters for every mobile employee, mechanics only move between the exits of their assigned rides. Because you've designed the regular paths for optimal customer flow, the shortest distance between ride exits will be along the regular paths, so that any mechanic-only path would entail detours and create longer travel times.