Hi Pierre,
Besides, I have a general question: when a package A is sent into NEW,
should I wait for it to exit the NEW queue before sending another
package B, which (build-)depends on A, into NEW?
Generally speaking: yes. It will prevent build issues in case B is accepted before A. I have personally seen that on the rare cases that I have uploaded a number of NEW packages in rapid succession.
In my specific situation, I violated the common sense recommendation because I was trying to get a number of packages through NEW for a time-sensitive COVID-19-related effort. That still hasn't completely sorted out but the urgency of the global need overrode the risk of build issues. In normal cases, avoiding build issues will be a higher priority.
I hope that example helps to clarify the judgment call needed for the situation!
-Olek