I assume we have problem with "scanlinelook exterior" as 90% of exteriors on this forum posted by new users.
Here is quick test to show how important is only materials to balance dark side/bright side of the force.
only .mxms are different and ISO in camera. no postproduction, no multilight, always the same settings of sky&sun
the most reflective white material is well known ARCHWALL downloaded years ago from mxm library and 3 sets of changes. I hope .gif is animated correctly.
ergo - this is very important to push newbies to right direction (understanding materials) not to photoshop.
edit: in my friend OPERA browser .gif is not animated so I post separated images. But it is more fun to watch it in one piece animated.
first: ( very well known pale, uncontrasted, overburnt whitewalled render)

and making it more convincing changing GI solutions

as I said in separated pictures it is not so obvious ... download them and compare animated