i can only imagine a situation where both hands would be on the yoke...that is if the a/c is certified for an Autothrottle app and landing. as in the B777.
other than that, the reversers are most efficient at speeds, so it can be argued that two-three seconds were lost if your hand was not deploying the reversers as the main gears touched.
and i supposed the same logic could be applied if you were to execute a rejected landing......
all the a/c's i have flown required one hand on each. surprise to hear that on the B737 really. never flew it though. only the 727.