Would it be beneficial to slant the reglet cut so it is also sloped? I feel if it is flat some water can also find its way behind it, although obviously less than the example you showed at first.
that was my first thought, but to get enough of an angle that it would affect performance you would probably risk chipping the brick. Even if chipping isn't an issue, It's sloped on two sides and has sealant, and the reflect gives the sealant several times more surface area to actually hold everything together.
