It is all in how you dress and set.
The worry point of a knot is that turn that is most likely to unload. On a bo'lin it is on the "top". This is where using a follow through comes in handy. It will make this turn wider and more pliable. I find a double bo'lin works well in heavy loading also.
Above is has a Yosemite follow-through
Note the tail runs fair with the working end of the rope. Knots are logical and can be expressed in several ways. The bo'lin has four, left right, up and down. Left and right are more mathematical parsing, but up and down determines if the knot tails into it's self, or out of it's self. For this reason some call them inside and outside bo'lin's
So prior to the Yos-follow through you have an inside bo'lin,
If you see me at the Expo, ask me about the Daisy-Chain Bo'lin (DCB). I've never had it lock, no matter how much we pull.
I've actually seen a rope break pulling, and it was not at the knot bend either. the DCB pulled apart easily.