I nearly always put PTFE around the olive, due to once a long time ago when i had around 6 leaks on about 6 joints, i was young and thought you had to get the stillies out for 10mm comp, well not that bad but in the end took them all apart and PTFE'd all ok, so ever since i do it 1st as someone said belts and braces, takes a little longer, but leaks cost time, money and reputation