I suppose I was unclear, I meant the value from a 3% conversion rate for a product is subjective to that product or niche.

I think the word you're looking for is "subject to that product...".

That isn't what the word "subjective" means. For each market, there are objective numbers to be researched and acted upon.

You mean 3% conversion being awesome "is relative to"/"varies by" a given product or niche.

"For each market, there are objective numbers to be researched and acted upon." and "A 3% conversion rate being awesome is subjective to the niche or product" are compatible statements.

EDIT: "subjective" is traditionally used when someone's opinions or biases are influencing a decision or conclusion, so I see where the confusion is here and the fault is mine for using that word. My main point is that there is no one-size-fits-all "good" conversion percentage, it's entirely dependent on the product and market.