Maybe I'm just unlucky this week, but so far the drop rate is preposterous compared to what we are used to, Even so, I really like the idea of being able to save a key and use it on the specific strike chest you want. I do have an idea/suggestion on the matter however.
If there were a vendor (or maybe even Zur) that would accept large amounts of Materials, Engrams, or whatever as a trade for a skeleton key it would help with the frustration and offer an alternate method of farming keys. Maybe set a limit to number of keys you can trade for in a week. Say 5?
Perhaps a selfish thought as I'm currently sitting on a heap of Spinmetal and Wormspore as I'm sure many guardians are. Thoughts anyone?