Depreciation on an RV is affected in a number of ways. Taken all together the result will greatly vary. I know from experience as a rancher that this also applies to ranch and trucking machinery such as tractors, balers, mowers, etc.
I have learned that factors such as original price, age, maintenance records, condition of unit, whether sold outright or traded, etc., and especially monetary dollar inflation over time, all effect the depreciation dollars.
If I may give one of our own typical experience , it may be educational. We have owned five RVs since our first one purchased in 1961. Four have been sold to a dealer at the time we purchased a new RV trailer to replace the old one. (We still own our 5th one.)
Each RV that we sold when being replaced, was originally purchased at a discount from the asking price. Each was sold to the dealer where we purchased the replacement RV. Each was owned for 10 or more years and each was carefully maintained to be in excellent condition when sold.
Each of the four RVs that were sold were owned by us over the years when monetary inflation was in effect, especially after 1970's. Due to the condition, and especially due to inflation, I was able to get a high price sold to the dealer, after I bought the replacement, new, RV than what I paid for the older unit when I purchased it, measured in dollars.
For example, I sold a JayCo 5th Wheel to the dealer where I bought our new Monty just four years ago. The JayCo was 12 years old. I received $1400 more from the dealer that purchased the JaycCo than I paid for the JayCo from the same dealer 12 years previous.
Yes, considering how inflation has depreciated the dollar, there was actually some depreciation. But measured in depreciated dollars there was actually no depreciation. However, also, as a result of inflation, depreciated dollars, the new RV actually cost more than it would have cost without inflation in the economy.
So depreciation can be accounted in a number of ways.