Why one bathroom shelf looks calmer than a full cabinet
A single shelf forces choices that a crowded cabinet lets you avoid, and those choices are what make the room feel settled rather than cluttered.
What usually goes wrong
Most small bathrooms end up crowded not because there is too little storage but because everything visible gets treated as storage. A windowsill holds three half used bottles, the edge of the basin holds a razor and a ring, and the towel rail carries whatever was damp last. None of it is chosen for the room, it just accumulated there, and the eye reads that as noise even when the objects themselves are ordinary.
The second mistake is buying containers before deciding what actually needs to be out. A jar or a tray does not fix a shelf that is holding twelve things when it has room for four. It just makes the twelve things look slightly more organized while still being twelve things.
What to do instead
Start by choosing one surface, a single shelf or the top of a stool, and decide it holds only what gets used daily. Everything else goes into a drawer, a box under the basin, or gets given away. Linen towels fold well because the fibre has some structure to it, so a stack of two or three holds its shape on a shelf instead of slumping into a heap the way thinner cotton terry can.
A glass jar earns its place if it holds one category, cotton rounds, hair pins, nothing mixed. Mixed contents in a clear jar look busier than the same items in a closed drawer, because glass shows everything at once. If the room gets hard directional light for part of the day, as many rentals with a single window do, put reflective or glass objects where that light lands rather than where they are merely convenient, since the light itself becomes part of the decoration and does some of the work a second object would have done.
A note on restraint
How bare a shelf should look is a matter of taste, not a rule. Some people want one jar and nothing else, others want a small collection of things they genuinely reach for. The measure is not emptiness, it is whether every object on that shelf earns being seen.