The beginner is taught that a Knight is worth three Pawns, and a Rook is worth five; Spielmann says that a Rook is worth 4.5 Pawns.
If Spielmann is correct, you can win many games from players who do not know the correct piece values; when you have two pieces against your opponent's Rook and pawn, you know that you are half a Pawn ahead, but your opponent most likely believes the material is even.
Half a Pawn is not enough to win, of course. In any specific position, your opponent's specific Rook and specific pawn might be worth a heck of a lot more than your two specific pieces!
Sometimes half a Pawn is enough, and you will win because your opponent (in effect) gives away material thinking it's just a trade; but even more often, something else happens.
Years ago, I overheard a Chess lesson given by Grandmaster Rossolimo. He said that you choose different moves when you're ahead, behind, or even; he said that the right move when you're ahead might be a losing move if the position is even, that you must always be aware of the changing situation, because a tiny mistake by either player might change the standings; and he said that you can win many games by having a more correct estimation than your opponent of who's ahead.
He was talking about the positional evaluation of the game, of course, but you can see how this applies just as well to the material evaluation!
I have won many games this way, and so I believe that Spielmann's piece values are correct, and that the values taught to beginners are wrong. An active player should be able to score 4 or 5 extra points per year by using this knowledge.
Of course, after you do this for a few years, you will get very strong at playing the endings with two pieces versus a Rook, or the Exchange up; and you will win even more games!