We use to have NO checks on water sets. Then things went down hill and then It depended on the depth of the water as to the length of our checks.

Not enough rats around my part of the state to fiddle around with wading out to set huts or what have you. While I have open water and I'm driving my land traps, if I see a rat swimming in the ditch and I have permission on the property I stop and quickly put in a pole with sudden valley clips for the trap and piece of parsnip. Pick up the rat the next trip and keep resetting till it sits empty a couple checks. That's how rat trapping works for me anyways. Poles make it quick and easy. No bedding a trap, finding a part of embankment that works, food source, or toilets etc. A little lure on some bait and they come to my poles.

I do the same when I'm In ND. But If I find any sign at all I have at least 2 stools about 18" apart at those locations. And In the spring I'm checking twice a day.
Pre set with bait and lure before the season opens and get ready to skin some rats once you start setting traps.
If you find culverts that are to big to work with colony traps set at least 4 stools or floats at each side of the road. Many times I have pulled up and taken 7 or 8 rats at each stop.