"The clock is on the desk."
Translation:השעון נמצא על שולחן העבודה.
It is sometimes used, but then it usually refers to something like a carpenter's work table. We used to say שולחן כתיבה, have we stopped? I wasn't paying attention. We do say מכתבה sometimes.
The ה is called the "hay hayediah", the identifying ה. It tells you what kind of table (שלחן is literally a table)
So if I understand your notes right:"shulchan is any table, shulchan table is more like a workshop table, and desk is either shulchan k'tivá, or miktavá?