Yes, I actually learnt that technique from a HGV driver when he was giving me some training on a 7.5t flat back many years ago.
His advice was, as you are approaching a turn off, be prepared to move out a lane in case there is a stream of traffic coming on to the motorway/A class road. Even if there isn't, it can be useful to move anyway in case an 'idiot' is flying down the slip road for whatever reason. This is especially useful in roads that pass through or close to city boundaries at peak times.
You simply look ahead to see if there is anyone on the slip road and glance in your rear side mirrors as you are passing in case someone is coming from a blind spot.
Ah that's interesting. I often see them move over into lane two well in advance of the junction (when I'm heading back home, going southbound). It's a junction where lots of HGVs join, as many industries in Derby and Nottingham will use it to get their goods onto the M1.
That's the roadmanship I was talking about earlier. Probably a better word for it, but it's being forward-thinking and anticipating things in order to help keep traffic flowing. I've said on here many times that I drive slower these days (to give people space and back off from potential problems) and my journeys are far less stressful.