In my experience* snakes are the MOST stressed right when we pick them up, so if you handle them for only 5-10 minutes, they hardly get a chance to feel safe with you.
What I suggest is to just sit down & watch tv or something while you hold a snake, sorta cuddling them to you so they feel safe & warm (they feel most afraid out in the
open & are more likely to bite defensively that way, especially if you move your hands suddenly, they assume it's an attack). Take at least 30 minutes, because during
that time they learn your scent & touch, & start to feel safe with you. Remember too that most snakes (like BPs) don't visually identify you...they recognize us primarily
by scent & touch, so don't be offended if your snake doesn't recognize you thru the glass/plexi, or at a distance...we're just a scary blur at that point, nothing personal.
BPs are snakes that like warmer temperatures too, so it's not likely they'll be over-heated if you hold one for 30 or more minutes, as other kinds might (since we're about
98.6* ourselves).
(*we don't all agree on this, plenty of ppl do the same thing you're doing, handling for a very short time.)
Snakes don't all have the same personality either, so if yours gets too stressed with back to back days of handling, he might need more time off. If your snake doesn't
feed well (reliably unless shedding), that's usually a sign that he needs more privacy. BPs are normally mellow snakes, so you'll have to "read between the lines" some.