Sorry, dent explain well
Packs don't expire, I let the injury time expire rather than using Reds to speed up (I have 87 Reds currently)
I'm not saying that Nord have not loaded the engine in their favour (it would not be good business sense to load it in favour of anyone other than themselves), but given all the posts on here from users who have plenty/none red packs who are not experiencing injuries on a regular basis, I'm just saying I think it's very random. JMO