Longer games compared to faster games

I can't play with the pressure of time at the moment.  I have to look at the situation and study it for a bit before moving.  It takes a bit of time for me to process what is going on.  Have there been any famous players who were horrible at blitz and bullet games?

Perhaps one of the main points of blitz is to find out "when to think" during a game. If you're spending a minute on each and every move, then you're not planning correctly, and ultimately doing it wrong.

You take time to think when:
1. You've yet to come up with a plan.
2. The position is complicated and requires calculation

You shouldn't (ideally) take time to think when:
1. The opening is something you're confortably in.
2. You have a set plan.
3. You're winning and the finish is strait forward.

 But on topic: If I remember correctly, Botvinnik didn't very much care for blitz games. I seriously doubt he was bad at them though.

5min usually gives enough time for planning. 1min not so much. Half the time I see someone shun blitz chess, its usually because they spend 1-2 min on moves that should take 1-2 sec. The only way to fix that problem (i.e. learn "when to think") is to play more blitz games.

I consider myself a reasonably fast player, but I do not play blitz games or any other of this kind simply because I could not be bothered. I would not enjoy playing chess at all if I had to race through my games.

Bullet isn't chess.

Anything less than 10-15 minutes (with an increment) is useless in my opinion. Fun maybe (for some)...but useless