In the entertainment trading card industry, actors in popular television shows and movies sign a designated number of trading cards which will be randomly inserted into a 6-7 count pack of trading cards. The number of cards the actor signs as well as the pay scale is negotiated by their agent and the marketing person in charge of getting the autographs.
Before any new trading card product is released, the company will probably publish a schedule of ratios for how many of each different kind of card you will find in a case. A case is usually configured as 6 cards per pack, 36 packs per box, 12 boxes per case. If the published ratio is 1:36, then odds are you will find 12 autograph cards in a case. But beware. What that could also mean is that the cases are loaded with autographs from relative unknowns or bit players whereas the 'stars' signed relatively few cards. The actual ratio for finding that one mystical scribble signed in your favorite robo-babe's or chisel-jawed action hero's own hand might be more like 1:399. The wholesalers and retailers are all going to be privy to this information, but they are probably not going to let the consumer in on this. In some instances, a retailer will actually buy a whole case just to rip open all the packs, find the autographs and sell them on eBay and to hell with trying to sell each pack. It doesn't amount to a huge profit and there is still risk involved, but it required little work and didn't take up any shelf space.
The number of cards an actor will sign depends in part on the fee and in part on that actor's perceived popularity. The fee can range anywhere from $2.00 a card to $25.00 a card. Everybody in this negotiation is at opposing ends. The marketing person wants lots of cards for the least money. The agent wants lots of money and doesn't care about the number of cards. The actor just doesn't want to spend a whole weekend signing trading cards. The trading card company is going to try their best to end up with all the actors signing close to the same number of cards with the lead actor getting paid slightly more. However, what happens sometimes is that the lead actor will only agree to sign a few cards and get paid a whole lot more. Some actors could care less about the money. They are worried about flooding the market with too many autographs, thereby devaluating their signature. Sarah Michelle Gellar, for instance, does not sign autographs for the Buffy the Vampire Slayer trading cards. Her signature would be worth a bunch. The Rock signed 100 cards for The Mummy Returns. He must be very popular. Angelina Jolie, on the other hand, signed 900 cards for Tomb Raider. Who's more popular is all just a matter of opinion.
It's also strictly a matter of opinion as to whether any of this stuff is worth anything. After all, it's just cardboard.