Given that some of the tighter areas of Class G are less than 10nm wide in places, that's a good trick if you can do it.
As I said, something else has to be used to make the possible +/- error smaller - line feature (handrail), more frequent position checks, suitable navaid that is capable of the required precision at that location etc
I frequently ask PPLs and CPLs why they check +/- 5nm from the track for obstacles. Most simply say that it is what they were shown. They were never given a reason of why 5nm was used and not 2nm or 20nm. Worse, they were never shown situations where +/- 5nm would not be enough. There is absolutely no explanation of the link between the size of the corridor and the probability of statying within it using different navigation techniques.
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Heading 365,
OK I see what you are talking about.
However,
If your track passes that close talk to the unit involved and get a service.
Yes a good idea to talk / get a service.
However, the pilot is still 100% responsible for planning and actioning the plan that will keep the aircraft outside controlled airspace - even if they have a comms failure or the unit is too busy to provide a service other than a basic service.
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Anotherthing,
It is surprising just how much all the GPS units have in common. Basic theory, performance, errors, mapping Datums, WGS84, built in database, approvals, direct to, nearest, pilot database, loading and crosschecking of routes are very common from unit to unit even if the exact menu / button pushes are different. Add to things like cross track errors, and the non-angular display of a CDI and most is covered without ever looking at a specific unit.