Shard size for OpenSearch optimization

Hi all,

I could see the AWS documentation specifying to keep the shard sizes between 10 GB to 50 GB for better performance.

What will happen if we keep shard size less than 10GB ?
Will it impact OS in any ways ? Like delay in shard allocation, slower upgrade process, etc…

And is there any better way like keeping the resource at specific limit to improve upgrade time if we upgrade from OS 1.2.3 to OS 1.2.4 with shard size less than 10GB ?