Ok we need to get a few things straight here. First off, the only difference between D and OD is the one more gear...OVERDRIVE! Besides the different shifter position, the car will drive/shift no differently in D or OD, except that it will have one additional gear (4th gear AKA overdrive) Overdrive is not part of the planetary gearset in the trans, its a 1.5" composite belt/band clamped/controlled by a servo, and a weak one at that!
If you leave the car in OD and launch it, you will still be launching in 1st gear!!!!!!! The same is true for launching in D. The tranny will HAVE TO run up through 1st, 2nd, 3rd gears before it even thinks about shifting into overdrive! This speed is generally around 110mph with stock gears...maybe higher?
You can go to the track and leave the car in OD and launch the hell out of it and run it all the way down the 1/4 mile in "OD" This does not mean the tranny will actually get into overdrive...it most likely wont with a stockish car and stock rear gears.
Roll racing is a different story. If the TV cable is properly adjusted and the trans is in good operating condition....then when you floor it from a highway roll it will immediately kick out of OD down into 2nd or 3rd gear depending on your speed. However, i would not risk heating up that OD band...and if i were roll racing i would toss it in D just before you hit it. This will put the trans it at least 3rd gear and when you punch it you will either drop into 2nd or stay in 3rd depending on speed.
Do not do the 1-d-1 shuffle to hold second gear...dont really mess with the shifter much at all. get in the car, put it in OD and PAY ATTENTION. It should become pretty apparent what gear you are in by the speed you are going and the revs you are turning. Dont beat on that OD band...everything else will take care of itself. If you want to shift gears...get a stick car!