For most rarities, and in many cases, I would tend to agree. Not epics that are available in glory packs, though. Epic is the most oversatured drop table in the game for any given key type that has them, and it will continue to get worse and worse because this is the home of all the Siegebreaker/Godslayer troops.
Warning: Drop Rate Calculations
For reference, the chance of pulling a specific epic, at this point in time, is about 1 in 4011 for glory keys, about 1 in 1382 for gem keys and 2 in 329 (about 1 in 164) for VIP keys. This means you’ll get on average, less 2 of every epic for each mythic you obtain with glory keys and less than 3/4ths of one for each mythic you obtain from gem keys. Assuming you just open these key types for mythics (and the currently non-existant “new kingdoms”), it can generally take a year or more to get enough extra copies of an epic to ascend it to a mythic from only having one copy. Your “one copy a month” is about what the numbers say should be happening, and it gets worse as the drop tables become more and more saturated. You actually got a couple copies per mythic draw, so you either got lucky on the Pyggra draws (and/or used mostly Glory Keys) or unlucky on the mythic draws and had to spend an above-average amount of keys. And these numbers get worse for us for every filler troop that enters the drop table, which, at this point, is at least two times per month (invasion, raid) in addition to the normal glory pack cycle.
About event keys, you’ll also notice they are weighted within a certain rarity to whatever the currently glory shop purchase is. So while the chance of an epic from event keys is about 9.6% and there are (currently) seven distinct epic troops in the drop table, the chances of pulling Pyggra after you have rolled an epic are 1 in 9 after that (or 1.07% overall on a given key) because you are three times as likely to pull a Rhynaggor as any other epic, because it is a glory shop purchase this week (by whatever backward logic they still use to justify that decision). So, you needed 11 copies, the average amount of event keys you’d need to spend would be about 1028 event keys. So pretty much right on the money there. You’d get Igneous to mythic at the same pace, if you haven’t done that yet, so that does save you some gems.
It should also be noted that Broken Spire doesn’t really have any relevant star levels available until we get one more troop beyond what we already have to bring us up to 20 total in the kingdom, for ten star. A Broken Spire faction would allow you to hit the troop requirement for 14 star with 22 of 23 total troops at level 20 (so you wouldn’t even need Pyggra maxed here). 15 star requires 24 troops at level 20, which will just be straight impossible very likely until the next Broken Spire event, as none of the doom troops are associated with Broken Spire, we are unlikely to see another mythic here until we get at least one for every kingdom, and bounty troops tend to enter at the tail end of a kingdom event as well. And 15 star is an irrelevant gold boost anyway, with 16 star needing another additional troop for a total of 26, and only 25 of them need to be max ascended. If we do another Broken Spire event, then there might be a relevant star attached to upgrading a troop (maybe even with the promise of another new legendary) and it would be a good time to “catch up”, if you were behind.
So, if you are just after stars, with that many event keys, technically the best plan would have probably been to stick to your original plan after committing to not buying Pyggra to mythic when it was first available (or Igneous, to have also saved gems during that event) and continue to get a slow trickle of copies each month, then a final push with event keys (if necessary) during the next Broken Spire kingdom event, whenever that might be. But you only saved 6000 glory, which can only be converted to 33 event keys or 300 glory keys, other glory packs, and irrelevant junk, so it was more along the lines of not feeding the meter a couple quarters and getting a $50 parking ticket in the mail. This risk cost you easily absorbed since you have a surplus of thousands of event keys, which would be akin to having a connection that could fix the ticket for you. You still only saved basically 50 cents, but it’s something, I guess.
So, realistically, I don’t think it is ever worth not getting a Epic rarity glory pack troop to mythic on the week it is available if you have the means to do so, whether or not you need the traitstones.
I’m mostly saying this to serve as a word of warning for others. The examples you provided for attempting to obtain Epic troops in this manner are an average experience of what you have to go through should you choose to skip the easy acquisition method, and not an edge case. Number of Infernus drops is not typical, either, but that should go without saying.
So, as that was barely tangentially related to the topic, I guess I should comment on the stuff available this week.
The Epic is pretty bad by any player usable standards. I expect to see him show up in stat-scaled content where he can actually take advantage of his kit.
Doomed Club has the unfortunate distinction of being the Doomed weapon that converts out green, with green being targeted by three separate empowered converters, including the one that converts to brown. As such, it is currently a bit harder to accelerate or set up than the Doomed Blade, which can be occasionally set up with a single blue match followed by a red explodestorm. It still has the abjectly terrible 10th upgrade that causes you to lose all your skull hits and extra turns with some degree of frequency, but with this allegedly being addressed in the future, it might still be worth going after enough scrolls for this 10th upgrade, but not pulling the trigger on the upgrade until it is actually changed, as weapon upgrades are completely irreversible (apparently, even for Support staff).