Two plural nouns together

When a noun is used to modify another noun (noun adjunct), it is singular. Only the head noun is made plural by adding an -s/-es.

A three-foot (not feet) fence. --> thee-foot fences
A laptop computer --> laptop computers
A window washer --> window washers
A tree house --> tree houses
A tea room --> tea rooms

An exception is "women writers".

Also
a systems engineer --> systems engineers

I have similar question, but not sure if these are exception cases, I have seen these
'User requirements Specifications' i am not sure why it is not 'User requirement Specifications' as I expect 'User requirement' will be noun as adjective for 'Specifications' ? also read an article from News 'The road improvements Project' ... why it was improvements not improvement? need to know if the 'impr

Hello, i was hoping you could help me with a noun modifying another noun.
Viscera eyes. It's a song title. Viscera is the plural form of viscus and a collective noun. Following by another plural noun of eyes.

I was trying to figure out what it means. But is it grammatically correct? Should it be viscus eyes?

AnonymousViscera eyes. It's a song title. Viscera is the plural form of viscus and a collective noun. Following by another plural noun of eyes. I was trying to figure out what it means.

Most native speakers do not know 'viscus'; they know only 'viscera', the uncountable collections of internal organs. Since it is a song lyric, 'viscera eyes' may or may not h

what if you are in the following scenario:
First-generation adultS are much less likely to have achieved a high-school diploma than their subsequent generationS counterpartS

there is more than one subsequent generation + adults demands counterparts to also be a plural

can we use "Ten Years Papers" term or we should use "Ten Year Papers".