For some users they do not have a problem entering their serial numbers , but when asked to mark their bills stamping or even hand marking is where they have a problem. To me the thrill of hitting a stealth bill far out weigh hitting a marked bill. But that is just my humble opinion. I will admit that I only stamped about 10% of my entries anymore and the fun then becomes a chore. THE MATH 10% OF 600,000 entries far outweighs what most members will stamp in their lifetime. I am happier getting stealth hits then hits of marked bills. Now I remember when I considered it a sin to enter a bill and not mark it, in fact at the start of my entering it was common to stamp both sides of the bill in bright red ink Now I seldom stray from black ink and use only one stamp. I have given most of my stamps away to other users MF uses two of my old stamps (maybe three). I remember in the early years having about twelve stamps on the go then the new bills came out and different ink was required.