Nothing cut in stone about a homes wood work. Most people try to keep their woodwork in "period" for the home, and to keep with its existing door/window design. IE: The standard 3.5 inch tall baseboard for the 70's ranch style home will look terrible in a 1930's Brownstone, as they were built with large wood work.

Crown mold profile and height should be considered while taking the height of the room in consideration. Anything over a 4 inch tall crown used on a 8 ft. ceiling height room, makes me feel like the ceiling is squeezing down on me.

It is all about keeping the wood components "dimensional" in sizing, to the rooms surrounding fixed dimensions. Such as, no 5.5 inch tall baseboard abutting to a 2.250 in. wide door casing.

Type in your browser "woodwork for houses" and then images. Lots of homes to be seen with various wood work in them, to help gauge your likes and dislikes. JMO

 

Our window/door trim width is 2.25 and our baseboards are 3.25. Would really like to go up some on the baseboard width though and then also have a crown that is appropriate. Thoughts?