I have 353.1 hours and 9840.4 miles on mine, without doing anything to them except tooth brushing the dust off of the dust seals each ride and popping them up each year to put some seal grease on the fork leg under the dust seal.
They still work great and have never leaked. But then I have never been in the water or mud with them.
Water and mud are the trade mark for my track in Sweden. This year it was too much. One month of raining in July. Not much but enough to keep the water holes full. Is the maximum range between 80mm to 130mm for WP as well?
I try to change my fork & shock fluid every year. They always need it. The shock oil smells like sewage, and doesn’t look much better. The fork is much cleaner. I try to do while the snow is on the ground. Nothing else better to do but maintain my bikes & work OT.
Here is a photo of the manual cover and page 17, with the oil level information. Remember, this is just a small boocklet that came with the 2000 Berg I purchased. It looks to be a guide from WP, maybe Husaberg used higher levels for MX and SM use.