Idk if I speak for everyone here when I say this but I think you are confusing faster orgasm with better orgasm. If you tense up your muscles, especially abdominal and pelvic muscles you should orgasm faster. I am, honestly, unclear as to the reason why but that much is very clear.
But if you go in totally relaxed and don't tense your mucles you will take longer to orgasm but it tends to be a lot more intense by my experience and understanding of others experiences. You can actually try to consciously not let any muscle tense even when close to getting off to really get a distinguished difference come orgasm.
Now as far as what people "always say", I think they are saying to lie down and relax as in "dont worry or overthink it" and/or suggesting that the end product is relaxing. the former is good advice and the latter is very true. But I don't think they are suggesting you should not tense your muscles. That is a great way to get a quick orgasm out. Though I will say that really relaxing your muscles should cause the better orgasm.
When you tense up you are putting pressure on the root of your clitoris. That nerve bundle is rather large roughly H shaped and extends down either side of the vaginal walls and often comes very near the surface in the rectum.
That pressure acts just like massage, but it's the muscles doing the work.
During sex the pressure also presses the penis harder against points which wouldn't get near the friction if you were relaxed.
My first wife could work her muscles and climax while listening to me talk dirty to her without any other stimulation.
Just remember those are the muscles kegel exercises strengthen, and while it can be of benefit, clinical studies have shown a loss of libido in women who overdo the exercises.
Personally,I have more intense orgasms and orgasm faster when I clench my pc muscles
Lol I never masturbate but lol I have my first orgasm the other night
Scroll Down to Read Other Opinions
What's Your Opinion? Sign Up Now!I think that's pretty normal. I think it has to do with your PC muscles. When I clench I notice that the frequency of my orgasmic contractions gets much quicker but I wouldn't say more intense. When I get close I like to press my heels together, though. Don't know if that works for girls or not.
Yessir it works for girls,but mine don't necessarily get quicker,it's more intense actually
Forget what everyone says. Do what works.
me as well ill shot half way across the room if I tense up.
Well what is an orgasm? It is when you muscles get really tense from sexual stimulation! So apparently for you in particular starting out tense helps to get a better orgasm. Different people have different 'kinks'.
As long as you have having good orgasms, just go with it and enjoy it! (I know I do!)
Sexual Relationships 
Sexual Health 
Most Helpful Guys