@Dougie_Powers_17
MTC is right when it comes to reports. Does not matter if any of us are online at the moment of the attack, reports always help when it comes to tracking and records etc. Its a quite useful option for the mod team so do it as much as possible (legit reports of course).
As for multiple reports, do not worry about that. If lets say you report one thread and another user reports that same thread too, both his and your report is nested under the main report and acts as 1 with multi comments. In other words no extra work at all plus better records for tracking!
And you only really need to report one spam thread and not all from one user if they are all duplicate. That way we will review the profile anyway and do as needed and that way you get to avoid any "reporting delay" that you mentioned above. If there are more different threads to be handled and not pure duplicates then report those too I guess.
EDIT, for the PM comment. Its nice when you report it view PM to a mod (you can also use group PMs I guess). That helps too but make also sure to use the reporting system as well so the whole mod team can see it. Reporting view the system rather then PM is better when it comes to tracking etc.