I have never been a fan of this sort of thing, and this game is starting to remind me why that is. Lottery only items for end game content can be extremely frustrating.
for example I have been trying to get 3piece Ather Mending since AA - HRC so far i have the neck and 1 ring but the other ring eludes me (yes i know there is a staff for the set i have it but it is terrible and just no). and since it is a bound item its not like i can give in and go buy one.
The rings are coffer only and although i may not get all 4 possible coffers every week I always get at least 3 of them and before SO and DSA came along i was getting all 3 possible weekly. but still no second ring.
This is why i have always been a fan of some sort of dungeon currency even given in small amounts so after a month or two if you do not have that one item you are trying to get you can still save up and buy it.
I think the real reason i am frustrated is I had a chance to buy an Ather Mending ring back when the BoE bug was active and i thought at that time, well i only need one more no point spending 80k on something I will get in a week or two... well here we are months later and still no ring.