Infrared Communication

I have another question:
I turn the LED ON for example 1000microseconds and then off, in other IR-Codes they do it like this:

void oscillationWrite(int pin, int time) {
  for(int i = 0; i <= time/26; i++) {
    digitalWrite(pin, HIGH);
    delayMicroseconds(13);
    digitalWrite(pin, LOW);
    delayMicroseconds(13);
  }
}

int time is in my example = 1000.
I understand that this is because of 38kHz, but why do the toggle so often, not only on/off every 1000 microseconds like i do?

greetings
bauerbyter
(and again sorry for my bad english ^^)