I dont want to turn this into a friction saver thread so we will leave it at this, but sometimes I climb 5 or more trees in a day, changing my TIP once, twice or more in each. Now everyday isnt like that, but IF I/we ALWAYS used a FS, ring or otherwise I feel like I wouldnt get anything done. Add to that the fact that for decades trimming has been done without them without widespread tree death and structural failure and it just doesnt seem REQUIRED.
All that being said, there is certainly a time and a place for it.