I’ve had the best luck by changing what I chill rather than adding more ice. I’ll pre-chill all the drinks in the fridge overnight so the cooler is just maintaining cold, not trying to cool everything down from room temp. That alone makes a big difference.
Another thing I do is separate drinks by type. One bin for sodas, one for beers, one for water. People tend to dig around less when they know exactly where to reach, so the lid isn’t open forever. Sounds minor, but it really slows the heat creep.
If it’s a long afternoon party, I’ll also rotate drinks instead of ice, halfway through, I swap warm bottles out and bring out a fresh cold batch. Fewer trips than running inside every 10 minutes, and the cooler stays useful the whole time.