This is my perspective as a management person:
-if you're written up and there's no steward, it's as if it didn't happen.
-if you're written up, don't sign. Not even rts. Just say "I'm not going to sign that." Writing rts yourself CAN be considered a signature but again, no steward no problems.
-if your pt sup is tellin you to go faster then say "I'm doing my best." You can't be forced to go faster. We can't even force employees to maintain best documented performance.
-over supervision is tough inside because the onus of proof is on you. But file away if you want for whatever part of the contract you feel was violated. Just remember, "work now, grieve later" and "work as directed"
Honestly, just do the best you can and follow the methods. A good supervisor will work with you to help you get to where he thinks you need to be. An ignorant management person makes threats. Grievances will paint a target on your back. If you aren't perfect, they will find something you don't do well and back you into a corner. Keep it simple, try hard, work safe and by the methods, work as directed
and if a supervisor is working then say "that's my work please don't move boxes." If they continue then document the time you SAW and talk to your steward off the clock.
I've seen a lot of poor managing over the years and some stupid union employees trying to make a point. The smart ones talk less, and listen and watch more. If you act professional and do what you're then you're gonna be fine. If you're ever don't know then ask the steward.