The manual d 0 help assist was actually a secret of mine but its like this.
When you set contest to always and d assist to 100 your still not going to get the contest animation even if its set to always contest, test it for your self. Even then its like the auto contest throws you out of position sometimes and you end up contesting to where its not even effecting the shot as much.
You have to set def assist to a certain level to even get them to auto contest a little more.
What I've experienced in playing the game is that they will STILL contest automatically with it set to manual def assist 0 more than often or ALMOST just as much when its set to auto contest always with 100 def assist b/c even with the considered high setting their still not going to auto contest always. Plus I like having that freedom of movement on contests and footwork.
Why do I jump? Well jump contests are better than just holding a hand up and like I say I try to shut mufs down but by tapping the jump button I've found that its more of like a quick jump contest which means they dont jump as high and you can recover a little better.
Contesting in the paint gives you the contact animation and what im saying is it doesnt matter what contest or def assist settings you have in the paint if your in position its going to give you the contact animation but that doesnt always mean that its good D necessarily.
I say that b/c alot of times even if you get contact it doesnt mean they are going to miss especially in one on one situations UNLESS you jump contest in which will make them miss more often then regular contesting. I really wish we could go up with two hands b/c when you watch roy hibbert he's seven foot so he doesnt have to jump as much which gives him more time to recover.
Just do this right, if you have two controllers test it out by playing one on one to see what kind of jumpshot feedback you get and it will show you what I mean. Its just all about timing and position, but im sure you will see that jump contesting is more effective in forcing a miss then just contesting. Dont take my word for it you have to test it out yourself dude.