You need to expand beyond that. The Classical by itself is not a good idea.
I speak as a Stonewall player with the same basic rule. Both the Classical AND the Stonewall should be a last resort, not a primary weapon.
1.d4 e6 (1...f5 you have to put up with 2.Bg5, 2.Nc3, the Staunton Gambit, and the Poisoned-Spike Gambit, here you have to deal with the French, pick your poison) 2.c4 f5 and now your 3rd move will be 3...Nf6, but don't just assume a Classical.
Both the Classical and the Stonewall should be played as a "last resort" when White fianchettos the Kings Bishop, beating you to the diagonal.
So after say, 3.g3 Nf6 4.Bg2 or 3.Nc3 Nf6 4.g3, then yes, Classical Dutch players should play 4...Be7 or 4...d6 and Stonewall players should be playing 4...d5
But this should not be Black's primary goal. After e6, f5, and Nf6, controlling the light squares, Black's main goal is control e4. Therefore:
1) If White commits his Knights such that they can no longer guard each other, like 1.d4 e6 2.c4 f5 3.Nc3 Nf6 4.Nf3 (Ne2 no longer possible), then pin the Knight in Nimzo-Indian Fashion, the extra move f5 is good for Black here! 4...Bb4!!
2) If White has not committed to both c3 and f3 with the knights, like 1.d4 e6 2.c4 f5 3.Nc3 Nf6 4.e3 or the London System (1.d4 e6 2.Bf4 f5 3.e3 Nf6 4.Nf3), Black should NOT play a Classical or Stonewall. Black should take the Diagonal that White did not claim and play 4...b6! And 5...Bb7!
You need to make sure you study both of these lines, and only play the Classical when White has played g3 on move 4 or earlier!
I recently adopted this opening against White's opening move 1. d4. I hope to show some games here, gone bad or good, and also hope others will share their games. To provide eachother with thoughts, ideas and suggestions on this what I consider a nice opening.
I got Simon Williams books and also purchased his online course on Chessable. Still learning and currently playing 4 games. One transposing from the Reti, another from the Englsih, and 2 direct ones.
By the way, I play correspondence chess. Hope others here will contribute (this thread is not meant to discuss other openings, or other opinions on how it is not a great opening... do that somewhere else
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