"Conflict on every page" is a truism of writing. Tension is what makes a book gripping.
You do need tension between your characters to make the story compelling, but I think it's also nice to create tension between the story and the reader. One way to do this is to have a mystery--have the reader be aware there is something happening in the story they don't understand yet.
Another way is to make your characters who are in conflict also both be sympathetic to the reader. In other words, make your antagonists three-dimensional people who the reader can also empathize with. This way, the reader isn't totally sure they want the protagonist to win--or at least, they don't want the protagonist to win too completely--because the reader doesn't want the antagonist burned too badly. The book's climax then becomes an ironic victory, no matter who "wins", because at least one sympathetic character got hurt by it.
When I rewrote my novel, I had two characters who needed depth because they were a little too blandly evil. I started digging deeper and trying to add layers to their personalities. I finessed their motivations, trying to make them more human and understandable.
I'm really glad I did it. I think the story is much more potent now; the stakes are higher and the tension is more acute, both for the reader and for the protagonist.
How many layers of tension do you have in your current WIP? Are the characters in conflict with themselves? Each other? Their world?
Is there a mystery to create tension between the reader and the story? Do you use other methods to create tension between the reader and the story? (If you do, I would love to hear about them! Please leave a comment.)
Are your villains sympathetic, or do you prefer to keep the story's struggle cleanly between good and evil? (Some consider that a crucial trait of high fantasy; the bad guys are supposed to be pure bad so that pure good can triumph.)