Quick answer: Safaris involve early starts, with morning and afternoon drives. The schedule varies by location and season.
More detail: Safaris generally involve early starts! The idea is to be out early in the morning, when predators may still be active, and when birds are also active. As the day warms, so the activity levels decrease generally, though the heat of the day can be a good time to visit waterholes, when animals come down to drink and bathe. In East Africa, close to the equator, the sunrise times don’t vary too much, and one will generally head out at about 06h00. In Southern Africa, further from the equator, sunrise times vary, so in winter one may head out relatively late, between 06h00 and 06h30, but in summer that starts can be very early, as early as 05h00 in mid-summer (Kruger’s camp gates open at 04h30!).
In East Africa we usually take a packed breakfast with us, and do long drives, returning for lunch and a siesta before a shorter afternoon safari. In Southern Africa the general routine is a long morning drive, of between 3 and 5 hours (depending on the venue), followed by a ‘brunch’, some time to relax or watch birds in the camp, and an afternoon drive (which runs till after dark in private reserves).
Private lodges may have a fixed routine, but in national parks such as the Kruger, Serengeti, Etosha, Masai Mara etc, one is free to be out of camp for the whole day, though we generally try to include some ‘down time’ to enjoy the lodge and take a break from being in the vehicle. But no matter what safari you are on, the days are full and rewarding!