A camel walks at about 4 km/h, which is slightly slower than you would walk yourself. That is the point. A desert crossing on camelback is not transport — it is the speed at which a sand sea makes sense, close enough to see the wind ripples reform and slow enough that the dunes change colour twice before you stop.
Almost every trek follows the same shape, because the desert dictates it: leave in the late afternoon when the sand stops burning, ride two or three hours into the dunes, camp, and ride out again after sunrise. The night is the reason people go. There is no light, no moisture in the air, and no sound at all — the silence in a dune field is the kind people describe afterwards as physical.
The deserts below differ in colour and grain more than in experience. Erg Chebbi is orange and steep; Wadi Rum is red sandstone with granite towers standing in it; the Thar is pale and studded with villages; the Gobi is cold, grey and ridden on two-humped Bactrian camels instead of dromedaries. What matters more than the destination is the operator: overloaded animals, short-roped noses and day-long rides in the heat are the marks of a bad one, and they are easy to spot before you book.