Yes LOL. Like air - "stuff" often expands to take up any available space whether absolutely needed or not

In my case, I wear specialty contact lenses in both eyes that require a preservative free solution for insertion/removal that is only available in 2 size bottles - a big and a smaller size though even the small size is a tough fit into a very small bag like the SAD21. I have to keep the solution at ready reach all the time in case I need to remove the lenses if something gets into my eye or something splashes my eye. It's a pain but well worth it for the quality of my vision with the lenses as I am otherwise legally blind without contact lenses ... On the (thankfully for me) rare occasions that I have to wear a suit or otherwise very dressy clothing, I do my best to squeeze it into my SAD21 as I like the look of the smaller bag if I am wearing a suit or otherwise more formal wear (or hand carry one of my small
Loewe bags that have a top handle.
The bolittle is a nice fit between the SA21 and the SAD29 for a crossbody narrow HMS bag and has no visible branding at all save for the subtle H design on the leather covered lock so definate "quiet luxury". The Steve Light Messenger junior is also a nice thin crossbody piece but definitely more casual (IMHO) with clear crossbody messenger design/vides. Ditto for the Evelyn - a more casual vide than the SAD.
I also think the Kelly Messenger PM is a good HMS men's bag in this category and i have one of them though it's trapezoidal shape and more than twice the width (approx 4 in at the bottom for the KM vs 1.9 for the SAD) do not wear as well (IMHO) with formal dress though I love the extra space you get in the trapezoid design and use it often. I could also say the same for the Lindy as a wider messenger style bag.
Just some rambling thoughts ....