Watch of the pitfalls when you choose the V-model! Do not assign a real hard entry and exit criteria to test approached and expect all those to work together before going to the next level. Spend less time in unit testing, integrate your system testing with your system testing and increase the time which is spent on user acceptance testing and don’t forget OAT. There are 3 things Wim Coremans propose to apply to avoid the pitfalls.