That depends on the highway. If it's a limited access motorway, like the interstates, Autobahn, or M-class then sure. Perhaps not coincidentally, that is where the right lane rule you propose is mandated.
Otherwise, it fails often. Reality is messy.
If you truly want to make the roads safer, follow the posted speed limits. (Energy follows the square of the speed.) Also, always ensure you leave enough room to stop (the "2 second rule").
I observed that it especially works best in concert with a rule that people entering/merging from the right have the right-of-way, since this reduces uncertainty around "who will go?" that I often witness here in NA (where "keep right to except to pass" is merely a suggestion, or not enforced even if enshrined in law).
Regarding speed limit, I'm not arguing against speed limits or adhering to them, and indeed the more consistent the speed of traffic, the safer it is. On that note, my observation is that simply adhering to the speed limit (and attempting to stay at that speed) means regularly passing vehicles -- that is, in most cases, people are indeed following speed limits and a "keep right except to pass" policy correlates well with maintaining consistent speed and flow of traffic. People who want to drive slower can stick to the right lane without any hassle or problem (it's accepted and normal for them to drive slow there), and those who are driving faster can safely pass and then return to that right lane. If there are deep flaws in this process, I'm absolutely not seeing them and have not observed them.
(yes, of course, the "two-second" rule makes sense and is a minimum IMO - I imagine if more people followed this, crashes would be massively reduced)
