When decorating a home, it is customary to put things on the walls. Large expanses of bare wall are unusual. Visitors will note the blank space as a peculiarity.
For the past year and a half I have lived in an apartment with a rather eccentric and demanding landlord, who asserts that any screw holes or nail holes must be patched up perfectly to avoid a charge against the security deposit. My solution has been to just leave the walls bare. For the five years before that, I lived in a converted attic with slanting walls which do not allow putting up pictures in the usual manner. I elected to leave the very few suitable vertical wall spaces bare as well. Although external factors led me to this situation, I find I like this arrangement.
I am of the opinion that thoughts should be guided from within. We should choose what to think about. Of course this is usually originates with our senses. Whether we use old-style books or magazines, or look at screens, we usually start with words and images to guide our thoughts. (The battle over advertising's imperative to impose their own agenda on our minds is the topic for a different day.) In the internet era it is more and more possible to actively choose. A TV channel was much more passive. The only options were to look for a new channel or turn it off. Even there, the TV screen was constantly changing, showing us new things. Today, clicking different places on a screen in sequence can lead to a stunning variety of different destinations.
Pictures on the wall never change. When we look at them they interrupt anything else we were thinking about and our perceptions of them take a place in our minds. Is there really anything that we want to endow with that power? Is even a picture of a beloved deceased parent really helpful? Perhaps you do want to remember them, but do you want your memories to be guided by looking at that particular patch of wall at that particular time? Most pictures do not tie us to something of such powerful emotional significance. Why should we think about that particular thing (yet once more) when we were in the midst of a train of thought we recently chose to start in on? The mind wanders plenty as it is, but do we really want to give another nudge to the wandering? We may feel we get so used to what's on the wall that we don't really register it any more. But more of our thoughts are governed by automatic processing than we are aware of. And if we really don't see it, there's surely no strong reason for it to be there.
Then there are visitors. What a first-time visitor sees when looking at our walls gives them an impression of us. But does a series of pictures, however carefully chosen, really convey what we want to convey? If we follow the standard rule that walls should be covered with things, then they can judge us compared to the other things we might have chosen to cover our walls with. But perhaps we would do better to escape that paradigm entirely, and with mind uninterrupted by anything on the walls, hope they listen more carefully to what we say, or think more carefully about what they say to us. If we want them to concentrate on a particular set of images, we can show them a photo album in some format or other (phone, tablet, paper book).
I recently saw at someone's home a sort of intermediate arrangement, which is presumably quite common. A large-screen TV had a looping slide show of pictures from a recent vacation. Presumably they enjoyed being reminded of that vacation. But they quite likely replaced it with a different set of pictures after the next vacation, or perhaps simply shut it off and had a blank large-screen TV on that section of wall.
Compare this to places outside your home. If you have your own office, the same considerations would apply, if to a lesser extent. If you go into a restaurant, the décor has likely been chosen to help set a particular mood, and quite possibly you chose the restaurant in part because of the "ambiance" for that particular block of time while you're eating. If you go into something like a Target or Walmart, you have put yourself in the world of retail commerce and probably aren't upset to be inundated with advertising -- some of it might actually be useful! If you go into the sanctuary of my Unitarian-Universalist church, you are typically wanting to nudge your thoughts in the direction of the profound or spiritual. Stained glass windows are in line with what you want to be thinking about.
In your own home, whatever is on your walls is bound to be relevant to a much smaller fraction of the things you want to be thinking about at any given time. Likely so small that they hinder rather than help you in your life goals. Maybe bare walls would serve you better.