In some cases, earlier signatures do command a premium. A period minor league autograph sells for more than a later major league one for many stars. Roberto Alamar signed his name Bobby in the minors. Those signatures are much rarer than the tens of thousands he signed in the bigs. Mattingly used to sign as Donny until 1983/84. I own several TNMT #3s signed and dated by Eastman and Laird, when they were at a convention pushing the book. I'd charge more for them than just a normal #3 that I had signed today.
On the Spidey book, it always bothered me that Romita couldn't bother writing out 1,000. It must have saved him five minutes, at most.
I remember when Jose Canseco decided signing his name JC would let him sign more per hour. Promoters put a stop to that thankfully.