Prep the chicken: If using breasts, pound to an even 1/2–3/4 inch thickness to ensure fast, even cooking. Pat dry with paper towels.
Make the marinade: In a bowl, whisk together lemon zest, lemon juice, olive oil, garlic, parsley, thyme, rosemary, honey (if using), red pepper flakes, salt, and black pepper.
Marinate: Add the chicken and toss to coat.
Cover and refrigerate for at least 30 minutes and up to 6 hours. Don’t exceed 8 hours, as too much acid can toughen the meat.
Preheat the grill: Heat a gas or charcoal grill to medium-high (about 425–450°F). Clean and oil the grates to prevent sticking.
Shake off excess: Let excess marinade drip off the chicken to reduce flare-ups. Reserve a small spoonful of marinade for brushing in the last minute if you like, but do not use marinade that raw chicken has touched unless you boil it first.
Grill: Place chicken on the hot grates.
Cook 4–6 minutes per side for breasts and 5–7 minutes per side for thighs, depending on thickness. Aim for a nicely charred exterior with light grill marks.
Check doneness: Use an instant-read thermometer. Pull at 160–162°F and let rest; carryover cooking will take it to a safe 165°F.
Rest and serve: Transfer to a plate, tent loosely with foil, and rest 5 minutes. Squeeze fresh lemon over the top, sprinkle a pinch of flaky salt, and serve with lemon wedges.