字符串指定间隔长度插入指定字符串

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace ConsoleStringSplitPlusSpecialChar
{
    class Program
    {
        static void Main(string[] args)
        {
            var  originalValue = "abcde12345fghig67890";
            var splitLength = 5;
            var splitSpecialString = "/";
            var targetValue = SplitStringPlusSpecialString(originalValue, splitLength, splitSpecialString);
            Console.Write(targetValue);
            Console.Read();
        }

        public static string SplitStringPlusSpecialString(string originalValue, int splitLength, string splitSpecialString)
        {
            var originalLength = originalValue.Length;
            var splitCount = originalLength / splitLength;
            var targetValue = originalValue;
            var splitSpecialStringLength = splitSpecialString.Length;
            for (var i = 0; i < splitCount; i++)
            {
                targetValue = targetValue.Insert((i + 1) * splitLength + (i * splitSpecialStringLength), splitSpecialString);
            }
            return targetValue.TrimEnd(splitSpecialString.ToCharArray());
        }

    }
}