In my case, there are land sales. As I explained, land sales comps prices are way way lower than the prices that I got from extraction methods.
Extraction is supposed to be market based. If you're coming up with really different numbers via extraction vs site sales then that literally means you're doing the extraction incorrectly. The most likely reason is the difference in construction costs prior to getting to the depreciation calculation. As I've been telling you, it's common to grossly underestimate the difference in costs by location. As well, getting to the real accrued depreciation is a common stumbling block, too.
Here's an example:
4903 White Court, Torrance 90503 A 2020yb home of 3433sf on a 6014sf subdivision lot, sold for $2,275,000
35283 Rebecca Rd. Yucaipa, 92399; a 2022yb home of 3178sf on a 11,862sf lot, sold for $875k.
These two homes are reasonably comparable in quality but very different locations. There's a $1.4M difference in the prices.
Land values for SFR lots in Yucaipa start at ~$200k, not zero. That means the 3178sf SFR+improvements sold for $675k above the land value. $675k / 3178sf = $212/sf inclusive of the garage, other site improvements, all direct and indirect costs and the developer's profit margin.
You already know about the lot sale in Torrance on Fiat St, 17176sf lot, possibly splittable, that sold as an SFR lot for $935k. The 3433sf house in that town sold for $1.3M more than the site value. $1.3M / 3433sf = $378/sf, also inclusive of everything.
No matter how you cut it, these similar structures had drastically different contributory values above and beyond their respective site values. Some it will be attributable to higher fees/permits between the two jurisdictions, some of it to higher labor costs being charged for the construction, but much of it will be attributable to the higher PROFIT margins which these costs services never adequately cover in the more expensive markets. You have to take these additional factors into account when you're using these residential costs services because they use a fixed profit margin (something like 13%, last time I looked) whereas in real life the profits are the residual between the costs and the sale prices.
Now the developers know how to hide their true profit margins in their construction cost breakdowns, but if you were to compare the cost breakdowns between these two projects you'd be seeing a BIG difference in many of the line items.