What you learned on the small rivers applies just the same as on bigger just scaled up . The little stretch of river I own the first time I started to fish it , I just applied what I had learned on other rivers & was straight into fish .
From my experience though once you change to big deep wide waterways like the lower Severn etc it almost can revert to lake tactics , looking for deeper holes on what can be mostly a featureless bottom & filling it in & without doubt the bank & marginal shelf is the biggest feature especially when the rivers are carrying more water .
Do miss the river fishing , just not enough time to fit it in at the moment.
Just hope there will be fish to go back to. otters are hard at work on all my old haunts!