When we first moved here, it was later in the year, October. Being that is rural-ish, a lot of people let their dogs free-range, and we used to (and still do) get occasional visits from area dogs.
The first dog who ever showed up was this big collie, good disposition, but I noticed his fur wasn't particularly well-groomed. Every month or so, he'd amble by, and I'd pick the leaves and burrs out of his hair, give him a quick brushing, and send him on his way.
One fine day in late Spring, Kate was outside barking, so I looked out, and there was the strangest animal I'd ever seen - looked like a giant shrew!
I went out, Shrew bounded right up to me, and I pretty quickly saw it was my old buddy the collie, shaved completely bald. Apparently, that was the owners' idea of grooming - one haircut, down to the skin, once a year.
That dog visited us many, many times over the years, always with varying amounts hair.
On dogs with thick undercoats, like collies, if that undercoat is not brushed out regularly, it get's matted and all you can do is cut all their fur off and start over. I had a dog like that, I had to take her outside once a week in wormer months, and every two weeks in the cold months, and use a special brush to remove the excess undercoat, which could take 20-30 minutes, and produce a furball the size of a basketball.
CD