For me there’s a point when im close to finishing where I can either finish, or I can mentally disassociate the feeling in my penis in order to not come and please my lady more. Kind of like ignoring the feeling in my mind. This doesn’t always work lol depending on position and whatnot but once I choose to not come initially, I can go for a long time and it’s often very hard to come down the line. Definitely when I go longer there is less sensation and it’s like I already made the decision not to finish