T>>Ну тогда еще проще — уменьшаем кол-во проходов цикла до минимума и комплексити падает.

//#define COMPLEX

#if !COMPLEX
using System;
using System.Collections.Generic;
#endif

namespace ConsoleApplication1 {
    class Program {
        private enum State { One, Two, Three, Four, Five }

        #if !COMPLEX
        private static readonly IDictionary<State, Action> _mapping = new Dictionary<State, Action> {
            { State.One, Action1 },
            { State.Two, Action2 },
            { State.Three, Action3 },
            { State.Four, Action4 },
            { State.Five, Action5 },
        };
        #endif

        private static void Main() {
            State state = GetState();
            #if !COMPLEX
            _mapping[state]();
            #endif

            #if COMPLEX
            if (state == State.One)
                Action1();
            if (state == State.Two)
                Action2();
            if (state == State.Three)
                Action3();
            if (state == State.Four)
                Action4();
            if (state == State.Five)
                Action5();
            #endif
        }

        private static State GetState() {
            return State.One;
        }

        private static void Action1() {
        }

        private static void Action2() {
        }

        private static void Action3() {
        }

        private static void Action4() {
        }

        private static void Action5() {
        }
    }
}

T>>>Ну тогда еще проще — уменьшаем кол-во проходов цикла до минимума и комплексити падает.

T>код поскипан
T>

if (condition1())
  action1();
else if (condition2())
  action2();
...
else if (conditionN())
  actionN();

update orderitem set qty = -100

public class Customer
{
  private ZipCodeValidationStrategy _zipCodeValidationStrategy;

  ...
  public string ZipCode
  {
    get {return _zipCode;}
    set
    {
      if(_zipCodeValidationStrategy.Validate(value))
      {
         _zipCode = value;
      }
    }
  }
}

G>public class Customer
G>{
G>  private ZipCodeValidationStrategy _zipCodeValidationStrategy;

G>  ...
G>  public string ZipCode
G>  {
G>    get {return _zipCode;}
G>    set
G>    {
G>      if(_zipCodeValidationStrategy.Validate(value))
G>      {
G>         _zipCode = value;
G>      }
G>    }
G>  }
G>}
G>

ZipCodeValidationStrategyFacory.GetByCountryCode(this.CountryCode)

update customer set zipCode = "любой невалидный zip";