The National Archives is equally incredible and responsive: I made a Twitter bot[1] to automatically post photos from the DOCUMERICA project[2], and found handful of missing scans (just a few dozen in over 10,000) in the process.

I emailed them to ask about it, and they responded in a handful of days[3].

[1]: https://twitter.com/dailydocumerica

[2]: https://en.wikipedia.org/wiki/Documerica

[3]: https://blog.yossarian.net/2021/10/25/A-small-documerica-twi...