focusing airflow is only really needed if you're using your case intakes as part of the cooling of a passive heatsink.
Otherwise, they just tend to add more noise.
A good example of this in action is the AP181 in the TJ08-E, if you take out the HDD cage and use a heatsink that'll be facing the fan, you can run a system in a semi-passive fashion and have it remain fairly cool. Even with mild overclocks.
I did some experimenting with this awhile back and using a passive power supply, GPU, & CPU. Results ended up being slightly less favorable. As the GPU would get too hot during gaming.
This was with a HD6970 & TRAD2, so not exactly a low heat output GPU.