There are generally two roasting cultures. As art, typically referred as Craft Roasters with the years of experience on roasting who relies on their ear (cracking sound), eyes (changing color of beans) and nose (smell on various level as roasting going on) and Technical Roasters who uses roasting profile system and depends mainly on the variables like time, temperature and velocity of the air inside the drum.
Having said above, it is not necessary that craft roast is better than technical or vice-versa. Neither craft roasters with their experience nor technical roasters with technical profiling necessarily produce better roast compared to each other.
Because the craft roasting needs a long experience and may widely rely on particular machines, I would like to share a general guideline of roasting temperature for newcomers on technical roasting.