Why do people queue up for 15+15 and never use their time?

I can't remember the last time I played someone who ended with less than 10 minutes. I don't see why they don't just play rapid.

Because there's enough backup time to consult the computer.

That's a sad way to look at things. I think the vast majority of players don't cheat. I sometimes end games with plenty of time to spare where I've only burnt time on what I feel are pivotal moments in the game.

Good point General-Advance. It is of no value to ponder the first 5 to 10 moves if one has the opening memorized. Build time on the clock for later when you need time for those "pivotal moments".

solascriptura

I'm a beginner, and rapid doesn't offer enough time for me. Since I don't know a lot of opening theory, I spend quite a lot of time in the beginning so I don't fall into traps or lose on exchanges that I didn't think over.

In rapid I either blunder something in the opening, or I loose on time at the end, even though I may have been a few moves away from mate. That isn't too fun for me.

If you're a beginner trying to learn, I think classical is the way to go.

I go fast in classical to build up my time later for serious situations, and in endgame planning and strategies.

I think there's an element of trying to punk your opponent by playing it like blitz and still winning. But if you actually get an interesting position, like mate in 5 or something, then you can take your time a little bit to finish accurately.

and they will blunder and offer a take back

Well, for longer time controls I see the benefits:
1. You can easily skip the opening without much worry
2. using time for pivotal moments in middlegame
3. End games. I would use most of my time that way.
4. I can get up and do something and come back! of course!

Q: "Why do many people behave in this ostensibly stupid way?"

A: "Because many people are stupid."