TOPIC: Does Image Size Matter?

I have been wondering if I have been using the correct image size with the Fuji cameras that I use. The camera manufacturer uses image sizes noted with an L, M or S and numbers like 3:2, 16:9, 1:1. I looked up the conversions and have them written down but not sure which I should be using...which is the best. So far I have not had any problems but then I would not know. I have the cameras set at L 4:3. Conversions are for example: 3:2 = 6000 x 4000 and so on. Which size works best with an HIP report? And no, I have not contacted the manufacturer.