A show of hands ... how many of you measure how often good customers visit your website, on a monthly basis?
I know, I know, the percentage of affirmative responses is under 10%.
Go measure active visitors on a monthly basis. If these folks are visiting an average of ten times a month, then why in the heck are you obsessing about optimizing conversion rate? Seriously, why? The customer is coming back every third day ... do you care if the customer converts today or Saturday? No. You just care that the customer converts this month.
But because you are obsessed about conversion, you offer 30% off plus free shipping ... and you get the customer to bite ... even though the customer would have bitten three days later anyway.
Measure this stuff with a purpose - you want the customer to buy something this month, not this specific visit. The more you focus on this specific visit, the more you beg the customer to buy something via discounts and promotions and phony optimization, costing your business the profit your merchandising team has worked so hard to generate.