Dope is the old method while teflon is the new method.
I prefer to first testfit the joint to insure that it is going to seal first
due to the inconsistency of some of the fittings nowdays (chinese crap!) and
then use teflon on them. I do make sure that the joint is tightened to the
point where it really doesn't need tape to do the job right but the tape
makes getting to that point easier.
The pipe joint is actually designed to not need any filler compound but that
takes longer and uses more force than using a lubricant to help in the job.

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Why isn't there an Ozone Hole at the NORTH Pole?