A flaw in my plan... perhaps?

After my recent epiphany, I have found a somewhat fatal flaw in my "play the story through" plan...

Stories are short and boring in sandbox games - it's the messing about that I enjoy!

Take for example Red Faction Guerrilla... I love trying to beat the pro times in demolition and transporter side missions... and considering that each sector only really has about 5 story missions TOPS that leaves a lot of open world to run amok in.

I'm enjoying the sense of nearing the end but part of me is aching to slow down and mine ore deposits and look for radio tags. "Why don't you then!" I hear you cry... 20 uncomplete games I repeat.