What patterns from the Gemma catalog do you apply in your projects to solve typical tasks?

In my C# projects, I often apply the following patterns from the Gamma catalog to solve typical tasks:

• Singleton — to ensure a single instance of a class, for example, for a configuration manager or logger.
• Factory Method — to create objects without tight coupling to specific classes, which facilitates extension and testing.
• Observer — to implement an event-driven model where objects subscribe to changes in the state of another object.
• Decorator — to dynamically add functionality to objects without changing their code.
• Strategy — to select an algorithm for behavior at runtime, such as different sorting or validation methods.

Example of using the Strategy pattern:

public interface ICompressionStrategy
{
    void Compress(string fileName);
}

public class ZipCompression : ICompressionStrategy
{
    public void Compress(string fileName) {
        Console.WriteLine($"Compressing {fileName} using ZIP");
    }
}

public class RarCompression : ICompressionStrategy
{
    public void Compress(string fileName) {
        Console.WriteLine($"Compressing {fileName} using RAR");
    }
}

public class CompressionContext
{
    private ICompressionStrategy _strategy;

    public CompressionContext(ICompressionStrategy strategy) {
        _strategy = strategy;
    }

    public void SetStrategy(ICompressionStrategy strategy) {
        _strategy = strategy;
    }

    public void CreateArchive(string fileName) {
        _strategy.Compress(fileName);
    }
}

This approach allows for flexible changes in program behavior without modifying client code.