I understand what you are asking.
At a given rpm and load, the engine will make the most power when the spark is lead by enough time to develop maximum pressure when the piston can apply the maximum leverage on the crank.
An engine that makes the most power at 3000 rpm with 34*BTDC will seem a little sluggish at 30*. You will see on the drag strip even if you can't feel it in your butt. I can tell you from experience that there is a range of timing that once it is outside of you absolutely can feel it in your butt.
Can a few degrees make a difference? Absolutely.
I worked with mechanical tech that had been involved in Stock Eliminator for while. While searching for 'a little more' they decided to set up the new Direct Connection race distributor like they had the points distributor. Unforunately they started running slower. They lost several weekends until they figured out that by eliminating the heavy spring to bring the electronic distributor "all in" earlier, the spark was retarding at high rpm. That was it. A few degrees retarded was enough to lose races.
You can see it here.
The main culprit is the time it takes for electronic switching. There's ways around it - one of the simplest being to compensate in the distributor. That's what the Chrysler performance distributors did. Because few people race in stock eliminator or similar classes, they don't test for and/or see the loss.
Another example here from Bill Baldwin in a FB video with a locked out distributor run up from 1000 to 6000 rpm. Almost 5 degrees 'lost'
When Hot Rod Magazine ran tested a 340 at Edelbrock in '69, the timing was set to 39* BTDC.
Two points about this:
1. Drag race and sometimes with dyno pulls, the engines are not heat soaked and the combustion chambers are relatively cold. Because the chambers are colder than a heat soaked engine, lighting off the mixture a little earlier can often make up for the slightly slower burn.
2. Burn rate does not neccessarily continue to speed up enough to keep up at high rpm. A slight advance in timing in the upper rpms often will make more power. Again few are involved in the types of uses where this makes enough difference to chase. But in those motorsports where it is, its worth pursuing.
