Heat oil in large skillet over medium heat. If you go high-heat you risk an automatic burnt layer of seasoning/sauce/garlic to the pan as you’re cooking.
To cut or not to cut? If you are putting your chicken in fajitas, salad or something where it needs to be cut I truly love to cut the chicken breast first so that each piece is coated in sauce and seasoning. However, sautéing the whole chicken breast works great as well especially for presentation.
Rub your chicken in chosen seasoning.
Add chicken to pan cooking for 5-6 minutes on each side until golden brown.
If you have a meat thermometer be sure to check for an internal temperature of 165 degrees.
Rest is always important. Remove the chicken from the heat and ideally cover loosely with foil for 5 minutes so the juices redistribute throughout the chicken and not run out when you cut into it.
If you are adding it to a stir-fry or something being cooked on the stove then definitely cut up the chicken and toss it into your vegetable mix altogether or visa versa.