It all comes down to the host not realizing what really works at the actual party. A million times I've had people give me their input about what should happen and when it comes down to the actual gig 99% of the time it all flies out the window. What they thought would work sitting in their living room sometimes doesn't fit. You try to follow their wishes as much as possible but need to use your experience to do the best job. In the end if everyone has a good time they're happy with whatever you choose to do.
You don't state if there's a particular reason for the 40/20 thing but I think if you mix it up for everyone you'll do fine.