Time
One (of many) blindspots for those who subscribe to efficiency practices (e.g., 'second brain') is that not all time (doing the same activity) is the same.
In the field of communication, meaning and value cluster together. It is up to thoughtfulness to strategize our personal, interpersonal, and collective resources.
We could be churning water in a pool of thin communication, not realizing there is no meaning to forage.
But the meaning is, of course, personal, and so is its location. It does not scale, there is no map, and it is shared slowly. If we run into a room with introductions, business cards, and scripts, we will miss it.