This doesn't make sense to me. If I inflate my tyre to max I can cycle to work. Later on, the tyre is a bit deflated. Enough to be OK to ride on if I'm careful about potholes. However it never deflates any further. I left it all weekend and checked it and it's exactly the same level of deflatedness.
I'm about to switch out the inner tube but before I do I was hoping to discover why, in case I waste an inner tube.
I would expect a slow puncture to make it go completely flat.