Travelling in Africa means covering big distances. Going for example from Johannesburg to Kruger Park is a 6 hours drive and going from Kruger to other parts of South Africa even longer, not to speak of heading up to the Victoria Falls or other top-rated safari countries. The transfers can eat your days.
Unless you enjoy driving or even preferring self-drive safaris, you should consider light aircraft transfers between the safari lodges and camps to have short transfer times during your African safari tour.
The light aircraft transfers cost slightly more when comparing them with road transfers for solo travellers of couples travelling, but they save a substantial amount of time. The flight transfer from Johannesburg to the Kruger lodge takes about 1 hour, comparing to the 6 hours drive this is really a big win. And the flights go straight to the lodges and you are on safari from the moment the plane lands.
For short transfers choose flying. It is the best way to get around in Africa.