GlassJaw
Hero
3.x heavily encouraged the participants to rely on the system, it's formulas and the results of die rolls to determine what is true in the game world.
I'll agree that 3ed is a rules-heavy system but I don't remember reading anywhere in any of the books where the authors encouraged the players to never stray from the rules. If anything, the complete opposite is true. The rules should be the foundation, yes, but when they get in the way of "fun", they need to be brushed aside, even for just a moment.
To which the DM responded, before the player could roll, "You cut him down and he falls beneath your blade gasping his last breath" (or somesuch). The player was looking to use the combat system to give credibility to his intent to attack and kill his enemy. The DM, having no real stake in the scout continuing to live, just had the scout die.
The player was really ticked over this.
Then he should get over it. The DM made a decision on the fly that the PC had a high probability of defeating the enemy and spending the time to play it out wasn't important in the grand scheme of things. He wanted to keep things moving. Seems perfectly reasonable to me. I do it all the time when I DM.
I'm fairly confident that what Wulf is saying about on-the-fly rulings is this:
a) Don't let the rules slow the game down to a crawl when they are not enhancing the game or making it more fun, and
b) Don't let the rules force you into spending hours and hours of prep time when they won't bring any more fun to the actual play session. No one cares how many ranks The Dark Lord has in Craft (basketweaving). I'm also fairly certain he maxed his Concentration ranks too.