I've been thinking on this very topic for some months, and would like to propose an alternate solution:
First, it's important to keep in mind that some ladies actively pursue reviews, or have a style that tends to attract the reviewing type, or else are high volume enough to simply pull in enough reviews purely based on the numbers....and some don't. 20 reviews is a reasonable amount to develop a real understanding of whether a lady is consistent, or not, and where that level might be at. It also provides enough input from a wide enough range of gentlemen (at least 20) to confirm an average appraisal of her looks is not too heavily influenced by someone who might have drastically different tastes from the norm. Allow me to suggest an alternative approach that levels the playing field all around, while not limiting the rankings to the very small handful of ladies who either only come from a certain style, or else have been around for a decade.
I would propose that TER create each lady's averages (used both as a search tool and in rankings) from the past either 20 reviews, OR past 2 years, whichever is longer. For example, if a lady's past 20 reviews are over a period of 4 years, then she falls under the qualification of those most recent 20 reviews. If a lady has 60 reviews in 2 years, then all 60 reviews play into her average. This provides a number of benefits:
1) While it's true that a lot can happen in 2 years, quite a bit more change can occur over 5, 7, or even 10. Ladies gain and lose weight (or otherwise just get surgery), improve in maturity and skills, ripen or begin to rot, clean up or start a drug cycle, sometimes go crazy, change their style, MO, or target audience, etc, etc. All of this can have a huge influence on her reviews, and it does not benefit either the gentlemen or the companion to see an average that is reflective of anything but where she is-and what she is capable of-now. Including who she was half a decade ago will often inflate or deflate her review averages, thus distorting a reference designed to help clarify matters for gentlemen.
2) Ladies often tend to gather steam on the review front early on in their career, and then review frequency will often drop off. Part of this may be due to seeing the same gentlemen repeatedly, and also because many men have expressed a lack of interest in "repeating what's already been stated" when discussing established women with many consistent reviews. Keeping the 20 review minimum for ladies who have accumulated less than 20 reviews in 2 years means the visible market/rankings are not dominated by the newer ladies (the very problem you are taking issue with now, thunder), and also ensures that ladies who are slow to receive reviews are still represented accurately by considering a span of 20 reviews, and not simply the 12 (or whatever number) they achieved over the past 2 years.
3) If an outlying review (good or bad, but we certainly hear the most about bad reviews) pops up, it's also going to shake out of her averages in 2 years, or after the 20 review mark for slow review receivers. Perhaps most importantly, I believe this may reduce some of the wailing and drama that we've all seen/heard with a bad review, because it gives the opportunity for a lady to genuinely move past an outlier, or a vindictive review. It might also encourage her to participate more in the review process (ie-being more reviewer/review friendly) to dilute the impact of that review over the 2 year or 20 review span. On the flip side, it means that positive outliers-sometimes written by a quirky reviewer, sometimes "encouraged" by the lady, or even paid for by the lady-only have a limited breadth of impact, which may (and I emphasize MAY) reduce the motivation in the case of false positive reviews. Another way of putting it, maintaining the risk while reducing the reward may discourage certain behaviors.
4) Lastly, and perhaps most troublesome to discuss, is the shift in scores post rankings. I think we can all agree this has had an effect, and regardless of whether you look at/care about rankings (some do, some don't), it does appear to have had an effect on individual scoring, ie-the review process of the individual reviewer. Creating a time minimum puts all ladies who came before and after that change on an even playing field, and additionally minimizes the effects of any other trends on a lady's reviews. Any reader may or may not feel that the present review approach is fair/accurate, and may feel that past approach(s) were more or less fair, but I think we can all agree that a review system becomes far less useful/accurate if a lady's valuation is based even in part on when she popped into the system and what reviewing trends she's been through, rather than basing her valuation in whole on her qualities as a companion.
As a last addendum, I would suggest that TER provide a showcase ranking and average score in profile only for those ladies who provide the following additional qualities. **Please note that like above, I am only referring to a lady's public ranking, and her on profile average score, and searchability through such. I am not recommending that TER remove such individuals' profiles entirely, or make them unsearchable though any other means save average scores.**
1) A continued presence on their profile via a live link to a site or ad. I've seen a number of ladies who have kept their profiles up for one reason or another (perhaps a hiatus, or I've heard that sometimes that it can be overly difficult to get voluntarily delisted). I cannot imagine the frustration a gentleman might experience when searching via average scores (with or without other search qualifiers) and receiving a list of potential ladies, and THEN having to go through and see who is even still active.
2) At least 1 review every 2 years. Fitting in with my suggestions above, this means that a lady's review average has at minimum something recent to suggest their average is actually valid. Obviously, if she is receiving reviews so minimally, then even that one review will play a major role in an average of 20 reviews. This means that if her performance or appearance has dramatically changed in the last 2 years, a single review over an average of 20 will reflect this heavily enough to make a noticeable dent (whereas it won't reflect much of anything in a pool of 60 reviews accumulated of the span of a companions' career). Ladies who have not received any reviews over 2 or more years often aren't active, or are avoiding reviews.
Again, all of this applies to personal/profile review averages, rankings, and searchability through either only. I am not suggesting that we remove certain ladies from the system entirely, or make the entirely unsearchable. A profile with only 5 reviews posted 7 years ago can still be valuable if the lady in question was a ripoff, and phone number search pulls up a string of names connecting the ad you're eying now to that old ripoff profile, and several others. I am merely suggesting that we tweak one area of the system that's been a long point of discussion in a way that benefits the gentlemen, and balances things out for the ladies.