It matters significantly. The airflow slider controls how much air mixes with the vapour on the way up, and closed means tight and warm - like drawing on a cigarette - while open means loose and airy like breathing warm air. For the XLIM platform, especially the 1.2ohm pods that most people start with, you want it towards the closed end. That tight draw gives you the warm throat hit and satisfaction that makes a cigarette switcher actually stay switched. If you have it wide open the draw is too airy and too cool and you will never feel satisfied by it, which is why many people think their device is broken when it is actually just misconfigured. If you vape a 0.6ohm pod and want a looser, more open experience, you would open it more, but for everyday 1.2ohm use, start with it mostly closed and adjust from there if you want it slightly looser. The adjustment range is forgiving - there is no wrong setting that will damage the device, only settings that feel better or worse to you personally.

I had no idea closing it down more would make that much difference. Mine was left at half open and it felt weak. Closed it properly and it suddenly felt like an actual cigarette replacement.

So that tiny slider is the whole thing I was missing. Mine was sitting open and now I have closed it it feels completely different. Wish I had adjusted this weeks ago rather than thinking the device was the problem.