I've deeply internalised that with flexbox, when using rows or columns that I need to visualise a row that holds multiple columns. And for a column, it's got multiple rows inside it. I literally have to visualise this in my head to remember the correct property.
Yes- justify-content: center will center items along the flex direction. For example, if your flex-direction is "row" then it will center your items in the middle of the row horizontally. align-items: center will center your items in the middle of the row vertically.
For example, justify-content: center and flex-direction: row centers items the same as align-items: center and flex-direction: column
If you choose "row", I see 1 row and 5 columns. So if I want more columns, I need to choose "row".
If you choose "column", I see 5 rows and 1 column. So if I want more rows, I need to choose "column".
When the content is wrapped, the setting is more intuitive, but most of the time, you don't want to use the wrap feature.