There is also the skill, easily learned by understanding how to do online research to find reviews and posts in forums like this one, of knowing what equipment you need to do the trip you're planning with a minimum of difficulty.

Deciding that a 4 season, 10 lb dome tent is necessary to do the PCT can be an easy assumption if you hear there can be snowfall year round in the Sierra - talking to veteran PCT hikers or Sierra hikers takes that assumption away again. You find out that in summer any 3 season tent or even a tarp works okay in snowfall at that time of year, if you are good at site selection and pitching your shelter with proper orientation and adequate guy lines. While there was the lady who went out with a tiny tarp, sandals and inadequate sleeping quilt and ended up causing a search after a panicked SPOT activation, there are also hikers who successfully hike great distances on the PCT with an accurately planned and carefully selected gear list including tarp, quilt, and other minimal gear.