Rachel Andrew:

An increasingly common question — now that people are using CSS Grid Layout in production — seems to be “What are the best practices?” The short answer to this question is to use the layout method as defined in the specification. The particular parts of the spec you choose to use, and indeed how you combine Grid with other layout methods such as Flexbox, is down to what works for the patterns you are trying to build and how you and your team want to work.

Amazingly educational article. I’ve said it before, and I’ll say it again: when you want to learn about CSS Grid, Rachel Andrew is the source.