ditto, but i cut back to the hairline. i otherwise find that the millimeter or two is noticeable in many lighting conditions or when viewed at varying angles. ie: from the side, with indirect lighting or when somebody is looking up at you or you being seated and looking up at somebody.

if you do not expose the hairline then these things are not issues. this is not due to a poor bond but in my opinion (observation) is due to the fact that bare lace glued or taped to the scalp will not have the same texture or reflection of light capabilities as your own bare skin which is what should be after your hairline ends.