For honoring, it really depends on your opponent and if you have company.
For example, if you have enemy of one and the right slayer weapon, you really don't NEED honor except for the luck bonus. But if you're just using a good sampire weapon, then you really need to honor your opponents. But sometimes it's just more convenient to kill one opponent then honor the next one, especially in low hit point mobs like the ML named monsters (Miasma, Coil, etc).
Once I spend half an hour waiting for a Dark Father to regenerate a few hit points, only to be interrupted in my wait by a bard and her stinking energy vortexes. That fight didn't go well at all. She wasn't a good bard and quit after a few minutes, leaving me with a mess and an unhonored, half dead Dark Father.
As I recall, I didn't finish it that day, choosing easier prey instead.