Anyone try the replica B-60 Fidelity Research VTA?

Nikola - A high level answer outside of the riddle scope. You have posted based on A and B conditions being met in the past.

A and B added to the Riddle.

What is the common element between A) someone that owns 20 (+) cartridges, and uses them all; and B) someone that changes VTA for every record ?

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Hint - This common element to A and B is measurable by observation.  
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Chakster - it is customary to provide a guess to a riddle.

Slavic Riddle Answer

Based on my personal, and friends experiences over the years, I have noticed;

"That both A and B types, regardless of the "titles" count in their library, will listen to a "set number" of repeatable records (reference points) , that can be counted on no more than two human hands. That is the common element."  

The most extreme case of this was a fellow I came across who used no more than 5 records. It took all day to play those 5 records with all his fiddling. He did this a couple times a week. It was evident that his vinyl routine was very therapeutic for him.

with that.

Lewm
CT0517 do you change VTA for every record.

Lewm
To change VTA for every record would require one to be a "B Type" if going by the Slavic Riddle. (grin)

Well, I have not been in this state for at least three + years now; although I enjoy talking tech/setup on the forum ......and find it therapeutic.

These days I am trying to get through the library. I select/pull 8 different albums, each time I will have a vinyl session. (each U-S cleaning session 15 mins, does 4 records). 30 mins prep while the gear warms up. I clean them and listen to them in full. Then I sort them into one of two libraries. The regular storage library, like where they came but with a label of "cleaned". The other library known as "I want to hear them again." All using an average VTA setting.

Some VTA information from the ET2 tonearm owners manual regarding getting in the ball park with VTA, before fine tuning.

1. If the measuring vertical tracking angle of a cartridge is high (greater than 22 degrees) its vertical performance will probably be improved by tilting it back (2 or 3 degrees) (front goes up) to match present vertical angles on records. 
   
2. If the measured vertical tracking angle of a cartridge is 18 to 20 degrees. It will probably perform best when its top is mounted parallel to the surface of the record. 
   
3. Some cartridges are very sensitive to small changes in VTA, others are not. 
   

Cheers

''To change VTA for every record would require to be a 'B type''.
But except for some weird masochist this make no sense.
The most records are 170g which means the same thickness.
Our ''initial conditions'' were parallel position of the arm in relation
to the record surface. There is then no need to change the VTA. 
By 180 g. records one would need to increase the VTA for, say,
1mm . I am not aware of other record thickness so some ''rule''
for ''all records'' does not exist.
If I was more brave I would say to my Professor: ''I am sorry but
 your question is not clear''. My experience is that most people
(including some Professors) have no idea what ''all'' means.
So how can they use this so called ''quantifier'' which function is 
to express generality in correct way ? ''All'',''most'', ''some'' are not
names which function as reference or denoting. ''Someone has
stolen my car'' express the assumption that ''there is a person
such...'' etc. That is why this quantor is called ''existential''. It
assumes existence of some person who has stolen my car. But
 if I forget where I parked my car or was drunk the assumption 
can't be true.