I do my rough out drying in paper bags and hollow forms in a box.
Both provide a humidity chamber and allow some moister/water to escape the container.
If I put s rough out in a paper bag and put that bag in front of a fan the bag dries causing the moisture to leave the bag faster and the piece will likely crack.
The high humidity in the bag or box keep the short grain side of the vessel hydrated so it does not dry faster than the long grain which is supplying moisture.
The box is simple, rinse the piece with water to be sure the endgrain is wet, towel dry, one day with the flaps closed,
one day with the flaps open, one day on the self, ready to sand and finish.
Most of my HF would likely dry quite well without having the box. It may be like a security blanket. The box requires the labor of closing the flaps and opening the flaps.
A kiln has to keep the humidity high and slowly reduce it. Professional kilns mist the air if humidity gets to low too fast.
Cracks are likely to form when one part of the form dries significantly more than other parts.
When a dry part needs to move and a wet part can't stress builds. Too much stress creates a crack.
Even wall thickness, curves that let the wood move (sharp edges don't move well), controlled drying = almost no cracks ( it is still wood)
Al