when to compile SASS

I am new to web development. I have read about SCSS/SASS and I realized it is not what the browser looks for, so it should be compiled to pure CSS. My question is did I get it right:

• whenever I make a change to my SCSS file, I should then compile it and then see the result.

• whenever I want to update my website, I should have a special script on my server side to translate the new SCSS files to pure CSS and that happens only once per update. (The number of CSS files is high and I wish to keep only the SCSS on my repository).

I would be thankful If you have any further information.

tnx a lot