You'd be mad to use trad. unless you really have to. Due to the cold I have tradded a bit last week and it was painfully slow compared to wfp.
On Monday, because heavy snow was forecast I wfp'd tops and tradded downstairs and struggled to make £75 in 4 hours - it was awful.
Today, because I know the forecast is for a thaw, I used wfp starting at 12 noon (with a bit of screenwash in the mix) and just put a bit of salt/grit down on a public footpath and splashed a bit of 5:1 screenwash mix from a squeezy bottle on the floor outside the custies doors.
In 4 hours, even with low water flow and rubbing snow/ice off of the hoses and gritting I managed £133.
Tomorrow I plan a full day wfp, but we shall see.