How to prevent stall on servo when returning to position 0

Hello,
I will soon play with an Arduino UNO and different type of servos, to meet the demand of teenagers that I try to occupy outside school periods.
I discover that along with them.
I'm trying to understand your codes. Excuse me for my ignorance.
From what I understood the different positions (angles) from 0 to 180 are declared in degrees!
Beyond these values the positions will be interpreted in microseconds (544 to 2400).
A question that comes up often is: How to set the minimum and maximum limits of a servo.
The code posed by "Southpark" seems to help that, but I do not understand the final loop

void loop()
{
   // Just loop through a few working values
   while(true)
   {
     myservo.writeMicroseconds(700);
     delay(4000);
     myservo.writeMicroseconds(1500);
     delay(4000);
     myservo.write(2400);
     delay(4000);
     myservo.write(1500);
     delay(4000);
   }
}

Why use write (x) and writeMicroseconds (x) in the same loop on values in microseconds?
Thank you for your explanations.
Best regards