Originally Posted by Kmxu

I think that UA's policy is that you cannot use RPUs for waitlisting for PZ spaces within T-24 h. However, a SFO UC agent was able to do it for me (T-2 h), but I did not get the upgrade cleared. I saw my name on upgrade standby list right away. So, this was an exception to the policy.
If PZ spaces (PN for GS) are available within T-24 h, phone/UC agents can certainly get the upgrade cleared. The failure rate was small for me. I could not get the upgrade cleared when the gate agent had taken over the control of upgrade process (typically, within T-1 h). So, if you see PZ spaces, you should call as quickly as possible.
Happy travels.