Product Image Resolution for Retail Store

Hi Team

I have read the documentation regarding the Image Size for the Main product image.
https://xtemos.com/docs/woodmart/faq-guides/image-size-content-alignment-product-grid/

As per the document the Product main image should have resolution width: 800px; height: 1200px;

But when I try to browse through all the product images your demo store I see different image sizes used.
Like:
1050×1200
700×800
700×700

We want to set the optimized recommended size so that page speed does not gets impacted and the cropping does not occur.

Can you’ll please suggest the recommended resolution which I can implement across the store.

Thanks