therefore the higher the playtime in the ‘window’ of reviews that you look at, the more likely they are to skew high.

Yes, I’m looking at 2 hours, not exactly high.

Two hours is the window for a refund, so I absolutely make a call within 2 hours.

2 hours is arbitrarily chosen as a catch-all. You can finish some games and refund them within that time, it doesn’t work well in all situations. It’s not some objective measure of how much time you need to judge a game.

specially a new / expensive game - hasn’t engaged me within that time, I refund it and move on.

The example is a free game. There’s also a difference between moving on and leaving a negative review