I think the importance/unimportance of ventilation has been misplayed for a long time. This is a Cal king, a snake which spends the majority of its life in dirt, under the surface.
The desert Cal kings live in burrows where the humidity is rather moderate. One can tell because their skin is not dried out when you find one. They are able to retain moisture under the surface, because there isn't too much ventilation.
When one finds a Cal king under a board, it is often a board where the grass has grown around the edges and the moisture is sealed in. Not damp necessarily, but not an open window either.
Too much of anything is not good. For a Cal king, lack of ventilation some of the time is not a bad thing, nor is alot of ventilation some of the time. If lots and lots of ventilation is provided all of the time, better to have lots of tight hides so the snake can avoid the dry air if need be.
I have a friend who for nearly 20 years used those First Phillips acrylic boxes with lids, no air holes (lids aren't tight, so air gets in, but ventilation is poor). He has some Cal kings that lived nearly 18-19 yrs in those boxes. Just going by that, I can argue that low ventilation is not a necessarily a terrible thing.
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Mark