I just put a new chain on my 1x7, and only measured once before I cut. I ended up one full link, one inch, shorter than my old chain. Shifting is fine.
When I'm on my 26T cog, the largest in the back, I'm right on the edge of it not having a full "S bend" as it passes through the two derailer pulleys. I can take a picture but really my question is this: if shifting is fine, could there be any other problem with the chain being too short?
I'm mainly worried about it wearing prematurely or something due to a higher tension, but it does seem that a single speed or fixed gear would be much "tighter" than this is.
Also, and I sort of am convinced this is all in my head, it seems like there is more resistance now then with the old looser chain. I've swapped back and forth with the old chain and tried to measure the deflection change among other things, but everything seems very subjective.