Task.WaitAll 없을 때 Task.Result 동작 방식

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

namespace app
{
    class Program
    {
        static void Main(string[] args)
        {
            var task3 = Method3Async();
            var task5 = Method5Async();
            //Task.WaitAll(task3, task5);
            Console.WriteLine(task3.Result + task5.Result); //WaitAll 없이도 Result때문에 기다림
            string s = Console.ReadLine();
            Console.WriteLine(s);
            Console.ReadLine();
        }
        private static Task<int> Method3Async()
        {
            return Task.Factory.StartNew(() =>
            {
                Thread.Sleep(5000);
                return 3;
            });
        }
        private static Task<int> Method5Async()
        {
            return Task.Factory.StartNew(() =>
            {
                Thread.Sleep(7000);
                return 5;
            });
        }
    }
}