Thanks for the responses! Is there somewhere I can find guidelines on how to get the most effective use out of priority numbers, are there any pitfalls or negative impacts to avoid?
Not really, it's a basic concept you just have to decide how to apply it.
e.g.
Call on TGID 1111 (prio 3) in progress
Calls on other TGIDs arrive, all with (prio 3) ==> ignore and carry on playing 1111
Call on TGID 2222 (prio 2) arrives. (prio 2) > (prio 3) ==> drop 1111 and switch to 2222
As a first responder I set my local dispatch channels to the highest priority, then fire tac channels next. Medical tac channels after that, and lastly medical consult channels. For a while during the COVID rush I bumped the consult channels up to second priority so I could listen to what was happening in the pre-hospital environment.