VTF and VTA- Constant or not?

In an ideal world there would be an ideal setting but in this one there is not. The lack of standards in the recording industry still amazes me after almost 50 years of listening. The question you ask revolves around the degree of trouble you want to take. Some arms have calibrated height adjustment that can be altered while playing ; it is therefor possible to get an ideal setting for THAT record and write it on the cover. WAY too much trouble for me, I have used such arms and will sometimes alter the setting if a record sounds bad but have a default setting I return to after playing. The instruments used in setting up the arm are already in your possession, your ears. Get a setting that sounds right to you on most of your records and don't worry about it. Why isn't there a more scientific method? Records are cut in different labs, cartridges have their styluses at different angles, we all hear differently. Use a good alignment tool, track at the top of the recommended range and adjust the arm height to a good compromise and you will be fine. In general raising the arm at the pivot increases treble and lowers bass , lowering it has the opposite effect. I myself as well as several others I have talked to usually have the arm lower at the pivot end than the stylus end as we find it gives the best balance, but that is for you to determine. There is more lit on these questions than you would ever want to read, sites like Vinyl Engine will cover everything in great detail. I am just giving my own experience. If you had a well equipped lab it would of course be possible to arrive at an ideal setting for any particular record, but there would be no guarantee that it would be ideal for the next record. Get it to where you like it and then , as Raul says, "Relax and enjoy the music".