Rand, srand, time. Why call srand only once?

Why should I call srand only once when trying to produce random number? I think it depends on the application.

Rand

Rand function, as you can tell by the name, is a function that generates random number. But is this really random?

Srand

Srand is a function that decides which number is printed when rand is called.

#include <stdio.h>
#include <stdlib.h>
#include <time.h>

int main()
{
  printf("----- Sequence #1 -----\\n");
	for (int i = 0; i < 5; i++)
	{
		srand(i);
		printf("%d\\n", rand());
	}
	printf("----- Sequence #2 -----\\n");
	for (int j = 0; j < 5; j++)
	{
		srand(j);
		printf("%d\\n", rand());
	}
}
/*
1804289383
1804289383
1505335290
...
two sequences are the same when using same seed nubmer 0 to
*/

Why is this a problem?

Srand is usually used with time function from <time.h>. Time function provides current time in seconds. By calling srand and rand pair multiple times within a second will cause same values to be printed.

Will give very long list of same number before switching to another number

Only call srand once at the beginning and use a (random-ish) number (ex. Time function, gettimeofday)