Institutional Hallways - Standards

What do other people do when designing distributed speaker systems in institutional hallways? What I've seen in the real world meets none of the best practices.
Like

Share this post

Choose a social network to share with.

This is a representation of how your post may appear on social media. The actual post will vary between social networks

I'm designing for a care home which has >100' highly reflective hallways with 8.5' gypsum ceilings.
Sources include paging and background music.
The design I'm supposed to complete has an in ceiling speaker every 30ft. 

What are the guidelines for designing spaces with a status quo this far outside of best practices?  Of course I can submit a design with extra-wide dispersion speakers every 10ft - 15', but the sales team with blow their lids at the price.

How does one even go about choosing tap values when the farthest listener is 20 feet away and the nearest is 2ft away?