Definitely not needed on a 4/4 or on a Plus 4 with the narrow wheels (sometimes called a narrow bodied Plus 4), and I would not fit it to a Plus 4.
All cars leaving the factory now seem to have springs that do not hold the hub under high pressure and the factory steering bearings are perfectly adequate.

As others have said greasing is important. A new car may be a little stiff for the first 500 or 1000 miles until the bushes in the hubs are "run in".

Peter

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