According to grilling guru Bobby Flay, when you grill (directly over the coals) hotter is better, and moving as little as possible will yield best results. Steaks can go 5-6 minutes on each side over a VERY hot fire and be done through (little or no pink left) but once it hits that grill, leave it be, put the lid on and step away (keep the lid on your grill as much as possible to keep the temperature up). Don’t move it around until you’re ready to flip it. Chicken goes the same way, but a thermometer is vital for chicken.
If you’re talking about really BBQing (indirect heat) low and long is the motto. We do a great BBQ Brisket that we start after Davening on Friday AM and serve for Shabbat. it melts, and also disappears! My DH makes the sauce from scratch, but bottled also works just fine.
Please don’t use Gas. Coals are worth the extra work.