The high-end cooler market sells one headline number above all: ice retention, quoted in days. Five days, seven days, longer. It is impressive engineering and it is mostly theatre for how people actually camp, because the number is answering a question that most trips never ask, while the things that genuinely keep your food cold get no marketing at all.
Who multi-day retention is actually for
Extreme ice retention matters if you are off-grid for a week with no resupply — remote expeditions, long boat trips, serious overlanding. For a weekend at a campsite near a shop, or any trip where you will pass ice along the way, the difference between a cooler that holds ice for four days and one that holds it for seven is irrelevant: you were never going four days without topping up anyway. You are paying a large premium for headroom you will not use.
The technique nobody sells you
A warm cooler spends its first hours just cooling its own walls and your room-temperature drinks, burning ice before it does any real work. Pre-chill the cooler with a sacrificial bag of ice, chill the contents before they go in, pack it full (empty space is warm air), keep it in shade, and open it as little as possible. Do those free things and a modest cooler performs astonishingly. Skip them and the premium box underperforms its own marketing.
What to actually buy
Buy the retention you will genuinely use. If your trips are short or have resupply, a decent mid-range cooler used with good technique is all you need, and the saved money is better spent elsewhere. Buy the heavy, expensive, multi-day box when your trips are genuinely long and unsupported — then it earns every penny. Otherwise the arms race is selling you a number to win an argument you are not having.