I have a rack with adult females that uses back heat and another rack for adult females that uses belly heat .. when it comes to follicle growth, breeding and egg production there is no difference AT ALL - all have healthy eggs and pretty much at the same time .. when it comes to feeding there is no difference AT ALL .. that is why I use back heat from now on - 1 large heat tape over the entire rack, it is much less work than with 10 small heat tapes

as for my hatchlings, when i first got a bunch of hatchlings i kept the room temperature at 86 24/7 with NO hot spot .. they ate and grew just fine, the females that I kept like this produced healthy eggs at about 18months of age