As acknowledged however being "supported" for the entirety of the "big lap" does not have anywhere near the same demand, on the pilot, as doing it without support.
Consider the segment logistics:
Someone, other than the pilot, researches & organises the availability of fuel, food, ground transportation & accommodation.
Sustenance, clothing, fuel may be carried by the supporting aircraft, giving the pilots aircraft greater range.
Assist with, even preparation of flight plans.
The non flying component forany long distance trip is huge. The assisted pilot is allowed to focus-on the flying alone.
Not so for the truly solo effort.
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