I think I’ve figured this tea out. If you were to smell the leaves after they have been put in boiling water for only a few minutes, you might find them to smell low-quality or even a little bit disgusting. Kenilworth OP is just not good for longer steeps, and definitely not second steeps; the leathery, morning-breath stench of spent leaves becomes dominant.
That said, this is not a bad tea at all, if you work within these constraints. It’s very fresh, invigorating, and somewhat full in flavor if you are careful to keep the steep under 3:30. If you do wind up with an infusion that feels oversteeped, try giving it a minute. As it cools, much of the unpleasantness and some of the astringency will go away.
If treated right, this is one of the best black teas I’ve had for its low price.