It is not the point of showing the surfer what he will get... If thats the case I can tell you there are many formats of showing the surfer examples of what he will get see in the members area.
Lets compare it with the "calendar model" which is still used by Pix and video and clubsandy.
Example:
http://www.pixandvideo.com/preview/gallery
That looks very different but it is very similar at your model.
Like I said, some sites choose to show the surfer only the 5 latest sets on the first page because they are unique and different from the others or because they contain a different model blablabla. If they would switch to any other model it wouldnt mean they would convert better....
And another point, some sites cant do it because their niche is very targetted and is not as wide as your site.
Your site can be devided in alot of subpages:
* Teens 1520 scenes
* Solo Girls 1207 scenes
* Lesbians 284 scenes
and so on
But if I was a site owner of a site that is only and only about facials and facial humiliation I would absolutely choose to only show the last 5-10 scenes on the first page of my tour. Why?? Because all the scenes are in the same niche.
I know a site (Lady Sonia) who could do it this way though... Why? Because i think she fits in alot of niches
* CFNM
* Femdom
* BDSM
* milf/mature
* Latex
* Fetish
and so on
So it all depends on the sort of site you have, the niche you are targetting and the scene variation.
This should explain why it wouldnt work for alot of sites!