So here's where I am right now:
My underlying question was based on that I have heard that a non-Israeli Ashkenazic Jew does not say E"K on a non-sabbath because one might lack the proper kavanah when saying it. So far I haven't found a confirmation of this. The sources seem to say that one doesn't say E"K on a non-sabbath because one might lack proper kavanah when saying the incense litany which is attached to E"K.
This still leaves me with the question of "since when do we remove a section of prayer out of fear that a person won't say it properly?"
The answer the commentators give is "it is limited and specific to the incense litany because the text of the incense litany says 'one who misses any of the ingredients is liable for the death penalty' - and since reciting is like offering, one who misses an ingredient in the SAYING is likewise liable for the death penalty."
This answer is hotly contested not only because not everyone accepts that reciting is tantamount to actual giving, but also because of which sections are held to this standard and whether all of the incense section would count. So the question of saying the incense at the end of prayers is unresolved in my mind.
This leaves the logical conclusion of "if I don't have to go to work so I'm not in a rush, should I say it?" but now I also have the question of "Is E'K inherently and inextricably a part of the incense litany or can it be considered on its own, and if it can be separated, why not say it as the fear about missing something is limited to the incense part".
If the purpose is to get to 100 blessings and E'K is useful for this, then why not say it everyday, just to be sure? Instead of relying on what I MIGHT be able to do if I eat enough, pray enough etc, why not fulfill the practice sooner with some "sure-thing" blessings and not pass up that opportunity? But can I see E'K as its own unit of prayer, so I can say it WITHOUT reciting the incense litany so I can avoid that other issue?