It often takes me that long, too, to do a thorough grooming, so no, you are not the only one. I used to spend up to 8 hours (over 2 days) bathing and grooming Piper for show. But for regular combing, no bath or clipping, maybe an hour or two if I do it often and don't have to fight mats. A thorough comb is what takes me time. I want to get right down to the skin and make sure I get those spots behind ears and under the arm pits as well as between the hind legs. Also between the toes and pads.
As for skills, I picked up lots of tips from watching others and asking for suggestions. That helped me a lot.
The nice thing is that if you make a mistake, it will all grow out and you will get to practice all over again. LOL.
Next time you go to a gathering, take your grooming tools and ask for help. Our club had some demos at one time or the other and we each got a chance to have a professional show us techniques. They would do something on one side of my dog and I had to try to replicate it on the other. It was very helpful. I also went to shows and spent a lot of time in the grooming area, watching others and asking questions.
Of course, it's not necessary to do a show groom all the time. If you just learn to do ears and feet, and maybe feathering if it needs to be shortened, you're way ahead of the game. Personally, I love the the way a Newf looks in a natural coat that has just been neatened up some. I love to see ears and feet trimmed, but the rest, for a pet, is just lovely as it is.
I used to let Hugo's feathers grow long. His front legs were a good 8 inches or more at times and you can't imagine how glorious he looked galloping across the lawn with his white locks flowing. I loved it, but it was a maintenance headache and required frequent detangling. Piper, on the other hand, looks best if her furnishings are neatly trimmed and blended in to her foot. She is just as pretty. Each dog is different to me and wears his/her coat best in his/her own individual style.
A clean, mat free coat is the most important, So, if all you can do is wash and comb, you're dog will look magnificent as she is.
Having the right tools makes all the difference. Pay particular attention to what tools the professional show groomers use. You don't have to buy them all, just invest in a few really good ones. For me, a really good pair of curved shears, a cheap comb and slicker brush, and really good thinning shears are all I need. I have other tools too, but these are my "go to" ones. The MCK and other special tools usually gather dust in my grooming kit. LOL. I do like a sharp pair of embroidery scissors for splitting those inevitable mats, though. I just have to be careful not to poke my doggie with them. Yikes!
Hang in there. You'll get better over time.
Edited to add: I think it's really important that the general public sees Newfs that aren't perfectly show groomed all the time, so they won't think all Newfs come that way or look like that all the time. After all, every Newf is an ambassador for the breed and should reflect the breed accurately. So even if someone doesn't want to trim every inch of his dog, as long as he's clean and combed, he's the beautiful example he should be.
