Peter Frimberley wrote:

It's only anti-stupid-car and anti-selfish-car. There's very little
point in trying to overtake buses on that stretch, you just get stuck
seconds later in the next queue of traffic anyway. Might as well just
go in convoy with the buses and the whole thing would run smoother
then.

If you are heading East (towards Highgate) then the road becomes 2-lane
again and eases up once you pass the first signal. In fact the road is
generally moving steadily once you pass the merge.

Heading West (towards Hendon) the road expands to 2 lanes just passed
the Addison Way junction. That approach to Henlys Corner is never quite
as busy as the one from the A406, plus there are some who will turn
into Addison Way anyway, either because they are going to Temple
Fortune (Golders Green) or because they are rat-running out the
junction (which actually isn't worth it unless it is very busy).

And that's assuming it's rush hour.