AS
CI100 points out, in Indian airspace it is only permitted in the "Oceanic" airspace, which is where it plays an additional risk reduction benefit due to the often poor HF radio quality/accessibility with Indian ATC.
In China, ATC typically instructs us to offset 2nm right of track as part of their RVSM program. Seems like a very sensible procedure to reduce risks inherent with the complex China RVSM procedures.
To me, SLOP seems like a very sensible procedure on two-way airways-- it applies the "rules of the road" where you drive on the right hand side of the centerline of the street (at least in progressive, civilized countries
), rather than on the exact center of the roadway with the logic that being equidistant from the pavement edge is the safest way to go.