Part of the question here
might be about the type of fish you're going after and where.
There are substantial benefits to anchoring up when you're after rainbows as, very often, they circulate in shoals in large stillwaters wheras browns are less inclined to do so unless focused on a particular food source.
Therefore, it's sensible to be more mobile when after browns and a controlled drift (with drogue) is a very useful standard set up.
That same set up is equally useful for finding 'bows and there are distinct advantages to deploying an anchor once you've found feeding fish in order to stay in the 'zone' rather than drift by.
Personally, I prefer to keep on drifting as I think it's a more interesting way to fish.
I have used anchors on the likes of Loch Shiel and Loch Shin when specifically after big brownies. Kind of a cheat really, get yourself up or downwind of some salmon smolt cages. Anchor up and fish lead core/sinking line and BIG fly techniques more often associated with the likes of Hanningfield or Rutland or Grafham..... trust me, it works
I think that type of fishing is the only time I have intentionally used anchors when after brown trout.
Thinking about it, when there used to be Sea Trout on Loch Shiel I used an anchor where the loch empties to become the River Shiel. Sea Trout had a habit of running one particular channel into the loch and an anchored boat was the best way to cover them.
Apologies, I'm reminiscing......again
Hamish