I dont think Elk meant if you have less colours it makes it better. Although alot of professional artists on forums do try and keep them low. So thats where hes picked up on it.
But i think hes trying to show that it can look just as good without using to many colours, and by using less colours more effectively it can look loads better.
Anyways sage bro, on the window part you forgot some of the perspective stuff. Like the face on side of the ^ triangle bit :o
But its looking great dude

Keep going!