Like others, I do it on a swim I e never fished, just take my rig off and 1 or 2 casts, but I know my water pretty well.
But this year I've invested in all the finding gear, Spod n Marker Rod, feature/probe leads... I will doing this in a week or 2 after new year when quiet.
There are a few swims on 2 of the waters I fish I want to get to know, and a few spots on a stretch of canal I've found.