Flip the burgers for best results
Flipping burgers as a career choice is probably not everyone's top aspiration but as a cooking method it works surprisingly well.
Your average burger will probably be 6 - 8 ounce (170 - 230g) in weight and it shouldn't be thicker than ¾ inch (2cm), otherwise it won't cook through evenly.
Burgers like above, provided they've been brought up to room temperature, will need roughly 6 minutes frying time in total for well done and 4-5 minutes for medium (slightly pink in the middle)*.
The method: get the pan or griddle smoking hot, non stick or cast iron won't need adding any oil. Set a timer to the required total time and cook the burgers, flipping them every 30 seconds. You can press them down with a burger slice in between flipping to get the outside more charred.
The flipping technique works equally well for steaks - and even better if you flip those every 15 seconds...
* for those reckless enough to have burgers medium-rare, take the timings down to 3 minutes. I know the food standards fascists won't let us even think about rare burgers but I know in America some very good burger joints will cook them thus. Of course your meat will be first class and the patties freshly made.