I was also going to make the point that digitalWrite() is not without its overhead, so calling it only when needed would be more efficient. Having said that, I'm sure that in the vast majority of cases it makes no difference whatsoever.
Still, I'd be inclined to write a function, or use one of the various libraries, e.g.
#include "Timer.h" //http://www.doctormonk.com/2012/01/arduino-timer-library.html
#define LED LED_BUILTIN
Timer t;
void setup()
{
pinMode(LED, OUTPUT);
t.oscillate(LED, 1000, LOW);
}
void loop()
{
t.update();
}