When I was living out in Oregon, 2 years ago, I traveled with a pair of 12 foot straps.
This first picture is showing that 12 feet was not quite enough for some trees.
This second is another tree where I used both 12 foot straps tied together to get a 24 foot strap which was just barely long enough.
These days I am in south Texas and six foot straps are long enough for most areas.
P.S. These are Old Growth Douglas Firs. Not even Sequoias. Unfortunately 95% of these old trees have been logged.
Those forests sure must have been something a 100 yr. ago.