The point is they are overtaking just slightly faster.
Trucks also spent long stretches in the same order, sometimes they change things up.
The speeds of trucks are measured on-board by a tachograph, so any big deviation can give them a fine, even if they weren’t caught on the spot.
And that 20 second delay really isn’t gonna impact the trip as a whole. Just rolling with it will make your trip less stressful, and therefore more enjoyable. If you’re late, rushing through traffic isn’t gonna make a significant impact, except on your risk of accidents.