Release Cadence

They haven't violated the cadence since they specifically said that some characters would have different sorts of events that wouldn't fall under it. Whether those other methods are reasonable is another question. Legendary events/hero's journeys aren't a problem so long as the characters needed for them are farmable, which they all have been (though some not for very long at the first instance of the event). You can get these characters 7* in a reasonable timeframe by farming their requirements. The heroic battles are another matter since at 10 shards a month it will take quite a long time to 7* these characters.