Well, then I haven't been clear in my explanations. I'm not suggesting that opening to an empty sequence loads the media any faster or any less media is loaded for the project. It's all loaded, regardless. But there seems to be some correlation between the speed in which all the media in a project loads and when Premiere decides whether a given render file is available and ready to play.
The point of creating an empty sequence and saving/exiting the project from that sequence is precautionary. It avoids having to load preview files for that sequence the next time the project is launched - because there aren't any to load. All of the media for the project still takes as long to load - which might be extremely quick on smaller projects or take several seconds on large ones (ex: hundreds of clips each with 4 tracks of audio). What is also critical for my workaround, is waiting for the all the media to load.
I have found this to be true on a recent project with nearly a dozen sequences - all of which were full of rendered previews. If I saved and exited out of one of those sequences, the next time I opened the project (and that sequence by default) most or all of the renders were "gone" while the other sequences were untouched.
If I saved and exited from an empty sequence, the next time I loaded the project and waited for all the media to load - as reported by Premiere - nothing was "missing" - green bars remained.
By the same token, even if I saved and exited from an empty sequence, but the next time I loaded the project, forgot to wait for all the media to load, and quickly switched over to one of the sequences I was working in, guess what happened? I was left with red bars on that sequence even after the render files loaded.