I guess I am one of those !
I have a backlog of at least 1000 taken over many years. I have not worked for a couple of years due to ill health and spend a lot of time scanning and editing. I try to upload a constant mix of old and new. A lot of my oldest stuff, late 60s and early seventies has yet to be see as I cannot get at the negs at the moment
If you said to me, give me 50 now. it would probably take me and hour and a half as I have a folder on the desktop with images that are ready to go and all the info, cns, histories etc is in another folder. The date and location three letter are part of my file names which makes it dead easy if there is nothing to add
The uploading is the easy bit. Some of my negs are dreadful and, if the aircraft is worth it, it can take an age to work them up to even an acceptable standard