Its like most of these calculations, the average person is fully reliant as to what they are being told by 'the system'. And human error never seems to be a mitigating factor, until its perhaps to late.
Over the past few years, I have found that trying to get my pension rights have been a never ending factor in not understanding 'the system' (am I alone?). I thought that before I retired, I had provided for later life, how very wrong I have found that to be.
Even when the governments tell people that the people don't claim their full entitlements, you always seem to hit a catch 22 obstacle when seeking help or making a claim!.
I was always told "that you will never beat the system", and the longer I live, the more I begin to believe in that saying :O).