Here's my method...
Gas grill. Charcoal's nice but takes too much advance planning; I'm not that well prepared!
Set all burners to HI and let BBQ achieve equilibrium. Should be over 500 degrees F.
I prefer NY Strip steaks. Should be at room temperature. Preferably never frozen, but if frozen must be fully thawed and at room temp.
Take the orders from your guests, ranging from medium to rare. If anybody wants theirs cooked more than medium well, give them a hotdog.
With BBQ cracking hot, put all the steaks on the grill, lined up in the same orientation. After 2 minutes, flip them all 180 degrees left, and turn down the temp to MED.
After 2 more minutes, take off the rare steaks and put them on a clean plate.
In 2-3 minutes, flip the ones on the grill 180 and rotate 90 so grill marks form little squares. Put the rare steaks back on the grill, flipped and rotated.
In about 2 minutes, flip and rotate everything 180 and 90.
Finish until each one is the right firmness for what your guests ordered. Should be abetween 1 and 3 more minutes, max.
A chef taught me a trick to check "doneness". I have heard some others do this too. Let me see if I can describe it. ...
With your left hand, close your thumb and index finger so they touch at the tips, like you're making the "OK" sign. Now with your right index finger, press the fleshy part of your left hand between the thumb and index finger knuckles. Feel how soft it is. That's how a very rare steak feels.
Now touch the thumb to the pinky finger. See how much the flesh firmed up? That's how a medium well steak feels. The longest finger gives you rare, ring finger gives you medium.
Remove each one when it has hit the correct "doneness", and let stand 3-4 minutes before serving.