The other thing I've seen is vehicles leaving on a slip road from a dual carrageway that's slowed to a halt then going round the roundabout at the top and back onto the dual carrageway. Saves all of a few seconds
.......this can save you more than a few seconds!
Junctions 10 and 11 on the M25 have standing traffic every day at rush hours.
I have used the technique to jump traffic taking note of a sign written van I am leaving behind.
Since I only drive at around 60 mph as I find it less stressful, sometimes the same van takes 15- 20 minutes to pass me once the traffic has got moving.
I know it's jumping the queue and questionable driver etiquette but it's dog eat dog on the M25 anyway.