Imagine you have 5 headaches, each 1 minutes long, that occur just 10 seconds apart of each other. From imagining this, you will have an imagined sense of what it's like to go through those 5 headaches.

And, of course, you can imagine yourself in the shoes of 5 different friends, who we can suppose each has a single 1-minute long headache of the same kind as above. From imagining this, you will again have an imagined sense of what it's like to go through 5 headaches.

If that's what you mean when you say that "the clear experiential sense is just as clear or unclear to me no matter whether I think about the person moments of the same person or of different people", then I agree.

But when you imagine yourself in the shoes of those 5 friends, what is going on is that one subject-of-experience (i.e. you), takes on the independent what-it's-likes (i.e. experiences) associated with your 5 friends, and IN DOING SO, LINKS THOSE what-it's-likes - which in reality would be experimentally independent of each other - TOGETHER IN YOU. So ultimately, when you imagine yourself in the shoes of your 5 friends, you are, in effect, imagining what it's like to go through 5 headaches. But in reality, there would be no such what-it's-like among your 5 friends. The only what-it's-like that would be present would be the what-it's-like-of-going-through-1-headache, which each of your friend would experience. No one would experience the what it's like of going through 5 headaches. But that is what is needed for it to be the case that 5 such headaches can be worse than a headache that is worse than any one of them.

Please refer to my conversation with Michael_S for more info.

*-1 points [-]