[the_hangman]

I'm not sure I follow. I just sat here with my 6S trying various ways of holding it for a good 10 minutes, and I can't figure out for the life of me what you're talking about when you say that you have to hold it lower to double tap the home button than you do to firmly press it. If anything, I find the exact opposite to be true: I need to support the bottom of the phone less when I am simply double-tapping on the home button, while I need to have more support towards the bottom of the phone if I want to firmly press it.

This seems to make sense, intuitively, as well: I'm applying way more pressure to the bottom of the phone with a firm press of the home button than I do when I lightly tap it, even if I have to tap it twice.

[k-mcgrady]

I think hand size is important to consider here. In order to reach the majority of my 6S screen I have my hand close to the centre of the phone. If I try to double tap the home button with my thumb it cannot reach unless I move my hand further down which involves readjusting my entire grip and I often come close to dropping the device.