Page Combining define as merge pages into single page. If you mean page combining like page linking for example you have 5 blogs and on each blog you have links to another 4 blogs then it has no effect on SEO it will increase your traffic with interlinking.
If you are talking about internal linking about website pages, then yes it has high impact in SEO as each web page has some PR juice to share. So its depends upon your linking technique. Without a offpage optimization a website page can get 2 to 3 PR based upon their internal linking.