If you focus on the PR of one of your inner links example) domain.com/bla/innerlink Will it just improve the SE rankings for that particular page or for the whole site? Thank you.
PR will be distributed from that page through internal links to your other pages. But PR only will not help your page or site rank better on search engines.
Deep linking with the right words are impt else it wont be that effective. Avoid words like "Click Here" / "Home Page" etc