Gold packs assign rares badly
Gold packs assign rares in a bad way for people nearing set completion, to the extent that it makes purchasing the mastery pass bad value for money.
This is based on my experience at the start of ONE. It appears to randomise the rare using the following algorithm "randomise set - > randomise rare from set". This is a bad algorithm for anyone nearing set completion as it will assign a set irrespective of how close you are to rare complete. Gold packs would work much better if instead they assigned rares by looking at all all currently currently missing rares in the standard and then randomly picking one. In my situation, it pushed me to rare complete in all standard sets bar midnight hunt, resulting in my mastery pass boosters mostly earning gems. I likely won't be buying the mastery pass for MOM for this reason.
The way gold packs function has been further complicated by the SIR release. It is very weird that you buy SIR packs, getting gold progress but the gold pack cannot contain any SIR rares.
Gold packs would work a lot better if you made 2 changes
1) all packs from historic earn gold pack progress
2) gold pack rares are assigned based on the sets that earned gold pack progress
This will sort out the above situations and provide a much needed improvement for new players that want to get into explorer and historic. It is very weird that standard legal packs are effectively cheaper than historic packs intuitively it should be the other way around.