How does penis size affect sexual pleasure during sex?

Researchers have repeatedly shown that penis size does not affect partner satisfaction during intercourse. Long or short, wide or thin, satisfaction between the sheets, is based much more on emotions and satisfaction in the other areas of the relationship, than on the size of a man's penis. [Edit: the question was "how does penis size affect sexual pleasure...," so it is reasonable to assume that the other relationship factors are not at issue. As an independent factor, penis size DOES affect sexual pleasure.]

A woman maybe leery about having intercourse with a man who has a larger than average penis, this will cause her to be tense and have a less than enjoyable time. A man who thinks he has a small penis may feel inadequate and be afraid he is not able to satisfy his partner, this will result in him being unable to enjoy the experience. [Edit: while the statements are true in general, and account for some psychological imact on sexual pleasure, it accounts for none of the pure physical, and only some of the inseparable physical/psychological.]

The reality is everyone should stop worrying, as women are able to accommodate any "normal size" penis. Any "normal sized" penis is as capable as another when it comes to receiving and giving pleasure. Normal size referring to what a man is born with, unaltered surgically, in either width or length. [Edit: "normal" size can range from <2 inches to >10 inches. Are you saying that there is no purely physical impact on sexual pleasure in that range?]

The truth is the vagina is about 3 to 4 inches in length, with sides touching, when in an unexcited state. The muscular structure is such that it will accommodate any penis size and then shrink back to it's normal size. [Edit: fact is, the vagina doesn't just expand and shrink so easily. If a woman has been with a man who is on the large end of what you call normal, it takes wuite a while (months) for her to completely shrink and the expansion is easier if she encounters a large penis in the future.] Men need to take their time and use additional water based lubricant at times and they can pleasure their partner with whatever they are given. It is all about timing and position. [Edit: TRUE.]

A man whose penis is on the smaller end of normal can achieve 100% increase in size during an erection, while a man who is on the upper end of normal may only have a 75% increase during an erection; this built-in compensating factor means that all men really are created equal [edit: you obviously have never watched pornography].