The use of hides, the temps they choose, where they choose to be in an enclosure, the affect lighting has and how these choices vary by the time of year with the climate offered, the differences made by age, what do they do when you spot clean the enclosure are some of the things that allow us to be in their heads...the choices they make. Our job is to interpret those choices.
I didn't mean for this to a be a urinating contest...I've been doing this a long time and I'm not a big breeder with a bunch of sweater boxes full of boas (-not that a properly sized opaque home can't be a good home because it can). I tell you this because I have been a student of reptiles by experimentation for most of my life and have yet to meet someone who has spent more time on WHY boas make choices. All adult boas here have 8 foot by 30 inch enclosures with in-floor heating. I've offered hides, lights, various forms of heat with cold sides to 65 and hot to 105, different substrates, climbing apparatus, swimming pools and experimented with the affects light plays in their choices and there is no question in my mind why adult boas will find less use for a hide.