I am doing a realistic flight from CYYZ to KLAX (based off this data) and am cruising at FL380 (like in that flight), at M0.85. According to my groundspeed, I am close to the same speed as that flight. However, a person behind me, doing the same flight is going 20 kts gs faster. Idk what to do in this situation, as I want to stay realistic. Is it realistic to speed up to M.86? Or should I trust the person behind me to slow down?