Does it help much at all....?

What you're actually doing by raising the hood is dispeling radiant heat, which will effect carb temperature & ambient air immediately around the engine. This will allow the engine bay to "see" fresher, cooler air, so yes it will help. While benefitting the engine if it's running (albeit a slight, yet measurable amount) you're also allowing hot air to leave which, as we all know, will eventually effect the life & appearence of underhood pieces.
Out here in the "desert village" those of us that know will actually STILL raise the hoods a bit on our patrol cars if we're stuck at a crime or accident scene for any length of time. That old ad about "heat being your engine's enemy" really is true......