Didn't say anything about not knowing where you are in IMC. You said;
even if you are in a nice jet, with multiple engines, there may be a time you have to land off airport so always have a field, open area, road, waterway etc in mind on which to land.
Let's say you fly a 777 from Europe to Australia, are you seriously suggesting having a knowledge of all suitable fields, open areas, roads and waterways in mind for a possible forced landing along the whole route?
Let's say you were the PIC of that A340 that flew from Singapore to New York over the pole. You're over jagged pack ice for 100s of miles in all directions, let's say it has a thick covering of fog and you're flying at night. Would you find a good spot to put the aircraft down in a forced landing at all points in this flight? No. You wouldn't.
The "golden rule" the OP was after here is that as a professional pilot you cannot plan for every conceivable scenario. Sometimes you'll be called on to react. This really is very basic stuff.