Don't forget about the spaces in between.
Focal points anchor a room, but it's not the only view a room offers. Designers have to consider how you move through the space, which items should come into view when. The aim is to draw you into and around a room, teasing with a glance of a room beyond but never revealing too much. Then there are aesthetic blocks, when you don't want to show someone access to something, but don't want them to realise it is shielded. This is usually the case for the kitchen. Most people want to eat nearby, but don't want to see the dirty dishes.
The corridor or transitional areas of homes often gets overlooked. It's not an area you'd traditionally invest in professional photos for, so they come up less on blogs or home tours. It can look messy to have all the doors open and to see into everywhere at once, so people rarely do it in imaged. But they will do it in real life, so it's the job of the designer to make sure all parts of the design sync nicely. Think about how rooms sit together, you want enough individuality in the spaces without making them look like they are from a different property.
This light, bright and minimal hallway W/C contrasts with the dark panelling and busy wallpaper outside. It's a little secret haven. The fixtures, fittings, proportions and floor continuity tie it to the rest of the room, so it doesn't jar.
The doorway going into this kitchen/reception room is painted in a contrasting colour, framing and curating your view.
If you are doing a modern kitchen extension in a period property, you'll have to tie the original features and proportions into your design. Continuous flooring and a similar colour scheme link the two spaces together.