When using compression fittings on copper pipe I've always hand-tightened plus half a turn. I think it was just a rule of thumb taught to me by my Dad.. I was wondering, however, how tight I should make a compression fitting to plastic pipe - more/less/same? My intuition is saying it should be the same.

If it makes any difference the pipe in question is 15mm Hep2O barrier pipe and I am connecting to a TRV. Incidentally, I am aware of the importance of using an insert.