Any idea what the current limit on mining expansion is? (& also how it is counted? It is obviously not a 1:1 with island chunk.)

I have a last section of a 4 piece island section that I am afraid to expand to as I did THAT stupid thing years ago & want to keep the ability to mine for food.

Last updated info on the front page seems to be from 2017, & I couldn't tell from the screenshot where that was in relation to the whole picture.

Thanks again to all who help people out here! : ) This game would be a lot less entertaining without you.