There are currently only two ways to get timeworn artifacts. There are 3 a run of DR or a possible drop in POTD. The POTD drop rate is abysmal. I've been doing 51-60 almost every day for hours since Saturday, mainly because it's just about impossible to go any higher than that, and I've gotten 13. Most of those were 7 I got on Saturday in 8 hours. DR for me isn't an option. I didn't enjoy the fights so I have not run that instance past the required time.
When you look at previous steps, there were a variety of options to keep things fresh. Fates drops were in more than one zone. Raid series (outside of the 180 step) allowed for drops from any entry in the series. Some steps gave guaranteed daily drops from certain roulettes or dungeon ranges.
And the step after this, raw emotions, are available in a wide variety of places, including a guaranteed drop from 70 dungeons. It's only this step that is so limited.
Can we get these drops in more places? It would make sense to make them guaranteed on a run of a 60 dungeon. Or possibly a daily for 50+. That would bring this step more in line with the other steps, which gave players a choice in the content they utilized.