I think I like that idea more. My lean to 40 years is just to satisfy the needs of some academic IPs. I suppose it wouldn't be difficult to categorise IP duration though
I think the applications could be protectable, not the pure academic research. If there is no clear practical benefit in 10 years, do not prevent others from working on those findings to try for something more practical.
To me, 5-7 years seems reasonable for technology inventions (patents), 7-10 years for books and other art.
> We find that almost all books, regardless of category, peak in the first 15 weeks after publication
https://epjdatascience.springeropen.com/articles/10.1140/epj...
A graph with sales per week/week after publication
https://media.springernature.com/lw685/springer-static/image...
Seems that 2 years after publication the number of copies sold per week declines by two orders of magnitude compared to the peak.