Yes, I have the same feeling, that a well chosen picture can make a difference between a post that gets more upvotes and / or comments and one that doesn't. No way to really know the CTR, we can only estimate it via those elements. Steemit has a "number of views" feature, but I heard it's not very precise.

Well said that pictures work well in all languages! I haven't thought of that, but it's definitely very true. SteemPeak is highly focused on the image(s) instead of text, so there the effect will be higher, I agree, provided that the viewer uses SteemPeak.