PBS is generally good for the top 10-20%
Even very junior bidders can usually get the days they want off.
If the pairings from the company are crap... Nothing can fix that.. not even line bidding.
BID realistically. When I was at RAH I was the BASE FO rep for S5 and MOST of the time when guys got crappy schedules it was because of unrealistic bidding. The MORE restrictions you put out there... eventually the systems gives you the finger and just starts assigning trips. ONLY very senior guys should be asking for specific pairings on specific days. Middle of the road guys might throw one or two curve balls at the system trying to massage their schedule. But the junior guys should ask for specific days... and maybe a restriction on show or release times ( but that could backfire )....

I have done both and both have advantages.