I was asking about the same for my Aussie who has nearly the same coat.
To answer your question....lots.
Collies have longer but just as dense fur. I have to chuckle a little at herding classes there are a couple rough Collies, very good performers but not quite as quick and agile as my Aussie. I've seen both Collies come in looking like winners from most beautiful dog contest. By the end of class after they have been down in the sheep muck very slushy and deep, they look like junkyard dogs, but very happy! I think I'd stop,at the car wash on the way home. Haha
We stop at a small lake and go wading or swimming. It's amazing how cold the water can be and the dogs don't seem to mind it.
I use the pin brush and a course comb for Sam's long coat shown elsewhere here. It works ok. I also have some horse mane and coat Detangler. It's ok but not perfect.
With winter coming on Sam gets a snow bath almost everyday so winter time is not a problem.