Interesting topic. I'd say that it depends on the game and if it has an in-game clock or not.
So, using a clock for a reference, I remember playing FFVII and hitting the 99:59 mark purely because of chocobo breeding. Who cares about finishing it anyways? Been there, done that, and Sephy's pathetically easy!
But yes, I got bored and stopped playing that.
When playing DWVII, I got over 100 hours on that, too (the clock goes above 100, which is good I suppose
). I think I finished it around 110 hours...dunno, but I did spend a lot of time on it.
Currently, I'm
still playing BoF3. As I went through the final city in the game, I maxed out my time at 99:59 and I'm just levelling there now until I can go back to the Container Yard and kill the Archmages and Berserkers no problem. I guess you could say that's a goal of mine, at the moment, rather than beating the game itself (which I fully intend on doing).
I know when playing Star Ocean 2 that I had a high time on that, but I can't recall what it was. I may play through it again after finishing BoF3, since it's a pretty fun RPG.
One game that I'm wishing had a timer is PSII -- I always spent so much time on that game, and to have a good guess for all the hours I put in it would be nice!