We raise cattle, and a recent industry magazine had the results of pretty thorough study on tenderness and grilling methods. Some points I thought were interesting.
#1 Searing a steak at high heat initially had no effect on tenderness, flavor or general "mouth appeal", but it did result in getting the steak done more quickly.
#2 Maximum tenderness was achieved by turning the steak every 2 or 3 minutes until done. (Seems to be because juices are redistributed upon flipping)
#3 Applying salt before, during or after cooking made no difference in quality.
#4 Letting the steak stand for 5 to 10 minutes after removing it from the grill is important to allow juices to redistribute within the meat.
#5 Drinking a cold Bass Ale while grilling puts the chef in a much better frame of mind.
These go against things I've been told, but this was a study that involved over 15,000 steaks being cooked,and both human evaluators and mechanical tenderness measurements. Actually # 5 is my own addition, but I assure you it has been thoroughly researched.