Hey Joan,
Well to answer your question first, I have been a keeper of various reptiles including bloods for some 25 years plus, won't give the rest away. At any rate, if you read the post more carefully you would see that the range is subject to change with room temperatures and weather conditions that affect indoor conditions and atmosphere well within basement and sub-basement levels (normal indoor conditions).
There are no sure footed way, to maintain and regulate temperatures within an enclosure unless you are running an airconditioner and a heater or boiler to keep your place cool and warm when temperatures dictate such actions. I don't think that that is neither feasible nor practical in any situation; especially when high cost of heating and electric are as high as they have been.
That said, the ranges that I have recommended are just that - a range with as mentioned, plus or minus a few degrees, on the lower end to the higher end of the spectrum. There is no way one can conceivably maintain perfect temperatures in their home or bed room or other etc., unless one has allocated and assigned a specific room with temperatures and moisture levels controled by scientific instruments that are well out-side the realm and budget of most keepers and novice.
My experience speaks for it self and the many herps that I have raised with nary an accident nor R.I, to count. In a 5-10 gallon aquarium you can raise a baby or juvie just fine for up to a year or year and a half with out any problem. Sure there are those like my self and others, that are handy with tools and designs that can steadfastly, construct a cage of melamine with out any problem. For some with little to no experience this can be a daunting task. I have built cages for many years and have posted my recommendation for building a melamine cage recently. With my recommendation for heating one too. Albeit, these are times when every one is an expert in their own mind, but that isn't enough when dishing out recommendations for someone with little to no experience; but the fact is that there are a myriad of ways to do things.
I personally would not recommend nor espouse such a recommendation to some one, with out first having tried it out my self or having had any or no experience in such cases as such feigning would no doubt lead to the demise or death of an animal. And I don't know about you, but I certainly wouldn't want that on my head.
So in closing I would for the record state that if there is ever any thing that I feel I can not with earnest or expertise answer for obvious reasons I would be the first to adhere to the "don't know don't tell" - motto. Hope that this answers your question and curiousity.