The magic of unbalanced coils. With HB's, there's a tolerance limit as it's difficult to get both coils to have exact resistance. At some point the difference becomes audible. When the coils are similar, the 'humbucker effect' kicks in which increases volume and mids, and reduces noise, high-end, and clarity. Unbalanced coils mean the entire humbucker effect isn't 100% present, so some single coil sound comes thru. That means a certain degree of more treble and clarity, and less midrange, depending on the difference between coils. I particularly like that for neck HB's, which can be on the warm side, and sometimes muddy. Clears them up. I make hybrid HB's by pairing up coils of existing PU's, as do some of the other members here.
The '59/Custom hybrid is a bridge PU with a huge difference between coils 4.1K vs 7K. That makes for a bright, clear PU, then figure in the A5 magnet which itself is bright and mid-scooped. It's popular with a lot of players, but not a PU for everyone. For me, a bridge HB with significantly mismatched coils needs a warm magnet, like an A2, UOA5, or A8 to have a balanced EQ.
I'd encourage you to use unbalanced coils in the PU's you wind. There's some nice benefits.