I certainly used to but less so these days. Mario Galaxy, NSMBWii and Mario Kart were probably the only games this gen where have have 100% completion and then a couple of others including Trilogy where I've had 95+% completion.

Try to, I'm OCD about completing things. I have 17 PS3 games with trophies, and I've platinumed 14, with 1 more coming in 30 min (Heavy Rain).

A waste of time there are so many new things to experience.

No, only for maybe a few games that I really like and don't get bored of.

Achievements/Trophies!!!!

i don't feel like i actually played a game until i am 100% done with it.
even if its 1 or 2 or 3 gen old , but some of the games are just plain boring i really hate "Intel" or hidden bags in shooters!

Almost never.

If it's RPG's, almost always, unless there are some ridiculous requirements that will take you over 500 hours to get them (like WKC).

The longest i've spend on getting 100% out of my RPGs was on FFX and Star Ocean: Till the end of time, both with saved games well over 200 hours.

No, I think I may have attention deficit disorder. Often I put a game in and it's out within 10 mins and I'm playing something random.

depends on the game & what needs to be collected...I'm not really a fan
of collecting 100 of items in games, shit gets annoyin & borin