RB wrote:

A wrap with thin (white) teflon tape

I use this on things I expect to take apart in the future.

A wrap with thick (yellow...gas) teflon tape

Would be my choice, on gas lines, see above.

Recto seal - never heard of it

Harvey's pipe dope with PFTE (teflon), is the stuff I have available and
use for things I don't expect to take apart.

Surely there is a consensus among those "in the know" as to what the
best technique is. Please let me know what it is.

The licensed plumbers used white teflon tape and pipe dope (don't know
which brand), when asked why both?, a: "it is cheaper and easier than a
return call".