I have to agree with John on his example because it happened to me (as a customer). Everytime I visit the doctor one of the first things they do is verify your insurance information, address, and telephone number. While the front clerk was updating my information, the record locked because someone in the billing department was editing it at the same time. However, it was roughly 30 seconds til it was free and she could see what changes the billing department had made. However, had the billing dept clerk gotten up and walked away with the record locked we could have been waiting...

You know, I'm beginning to think that Corporate "Wellness" programs consist of people getting up in the middle of updating data and taking a brisk walk around the office. ;) [just kidding]

Seriously, I think the vast majority of editing sessions (from the time someone starts typing to the time they save) is shorter than many think.

I understand your points. I'm not saying that pessimistic is the only way to go. If a client needs something more, it can be done. Is it a little more work? Perhaps. This is a topic I always raise with clients at the beginning (and often they have their own opinions based on their workflow). It's worth noting that certain DB designs may positively (or negatively) factor in to how much impact pessimistic/optimistic may have.