The thing is anytime you cut the guard hairs you have the possibilty of changing the coat texture. We see it a lot in Newf's as they are scissored extensively for dog shows. Scissoring has ruined the coats in some Newf's in the area's they are scissored for example paws, ears, chest, pants etc.
What we normally recommend for double coated breeds is a full groom to get the under coat out. Then every week for a couple weeks to bring the dog back for a complete brush out as there is coat that has been loosened which will still be coming out but wasn't ready at the time of the grooming process. Or the owner is advised to brush out at home. During a normal grooming session all groomers clean the pads on the paws & tidy or at least should
and for some big coated breeds such as Newf's the belly's are shaved after their show career to help keep them cool. We shave our Newf's belly's from chest down and they are much cooler.
If you groom at home when you have your Shepherd suds up take a brush over him. This gets a ton of undercoat out. If you have a hv dryer when semi dry start blowing & brushing then blow out until 110 % dry then take a slicker and line brush then a rake etc.
There are a few double coated breeds that even when the owners have been warned the coat may not come back in properly still insist. It is after all their choice
The owners have been very happy and have advised their dogs are much happier, they had less shedding (perhaps just shorter hairs) and the dogs are cooler. We also had a Newf that was 12 years old and HATED being groomed. So for her shaving her was a blessing, she was happier, cooler and she didn't have to be groomed as often or stand as long. Her coat did not grow back in properly the first year, but after that she did grow back in properly.