The hitch is dressed and set tight enough to provide enough grip for the applied load without being tighter than necessary.
To prevent failure in slippery rope Heinz advises adding a round turn to the 4/2 knot, creating a 5/2.
In practice it helps to insert the thumb under the lower turns to facilitate threading the tail.
A stopper knot is added to the tail after tying to prevent failure.
Incorrect tying - by not passing the tail behind the standing line after looping - can lead to failure.