Adjustment is a personal preference like everything else in this business. SOme like the plug and play systems and others invest time and money for SOTA on everything. Its crazy only if you don't value it. I will admit however, the rega arms do make it a challenge (at least the older ones)
I do not adjust every one but do adjust based on my knowledge of my collection and general thickness of the record. If it is a new record or one i dont remember, i will adjust to see if i can bring out any more detail. I listen for the clarity of the lows (does it get muddy or sharper), are the notes on a piano clear and crisp versus soft. Those are my typical things i do. I am not a great technical listener, but when i adjust, i know when it gets better to me.
I do not adjust every one but do adjust based on my knowledge of my collection and general thickness of the record. If it is a new record or one i dont remember, i will adjust to see if i can bring out any more detail. I listen for the clarity of the lows (does it get muddy or sharper), are the notes on a piano clear and crisp versus soft. Those are my typical things i do. I am not a great technical listener, but when i adjust, i know when it gets better to me.