I sleeve all the cards I put in pages. It reduces the chance of damage if I have to rearrange them later.
One more detail...I sleeve the cards with the opening at the bottom. It makes it a bit trickier to insert them into the page pockets, but it leaves no part of the card unprotected. The closed end of the sleeve protects the top edge of the card from dust or anything else that might fall into the open top of the pocket.
-Tom
Ted Musgrave card collection 98.9% Complete: Cards Known: 1013, Cards Owned: 1002
I prefer the company of people who disagree with me for the right reasons over the company of those who agree with me for the wrong reasons.