. . . on the New&Followed when I see person X, Y or Z posting in the 4 threads we both frequent, I can just click "all seen" there and just visit one of the threads to see the image once, so that helps.
At vB, when the forum page showed that Person X had posted two minutes apart in Threads A and B, I sometimes skipped checking the latest in Thread B if I'd seen all in Thread A. But how do you know you aren't missing something in B that was posted since you last looked at it and before Person X got there?