In the peak of summer I had to change my day wear moisturizer, my usual was just too thick and felt heavy from sweating. Also switched out my body oil to one that was faster absorbing.

Not really but I probably moisturise more in Summer after being outdoors.

I change it if my skin lets me know it needs a change but pretty much all I do is to add a facial oil in the evening. This is mainly during the cooler months when I might have heating on at home.