I assume you'd put the equipment on the shelves. For this, 30cm is not deep enough. You want at least 40cm for the equipment. The trend is for small and shallow, but much stuff is still big. You want as deep work area as you can get but still be able to comfortably reach the front panels.
In my setup, I have a 55cm table (too narrow) and a free-standing 40cm shelf behind it. The shelf would be too narrow, if it would be against a wall. But it is free standing and I can walk behind it. This is the greatest feature in my lab! I can arrange and re-arrange the cables as I need. getting stuff in and out from shelves is not an issue, I have enough mains connections and I don't have a cable soup on my work area or under the table. If I ever set up another work area, I won't put my table along a wall, I'd put it sideways, so I have access to the back side as well. Just something to think about...