En el artículo To Grid or to Flex? se analizan las ventajas y desventajas de realizar un diseño con CSS Grid o CSS Flex:
What surprised me about reading the responses in the thread was the number of people stating that they would only use Grid for page-level layout, and flexbox for everything else. If you take this as a rule, then you’re severely limiting yourself when it comes to Grid’s power. The main piece of advice I would give is to take every design individually, analyse the options available and don’t make assumptions about which technology you need. Here are some of the questions you could ask yourself when it comes to choosing a layout method.
Often, if you’re having to use calc() a lot to get precise track sizes (factoring in gutters, for example) then it’s worth considering using Grid, as the fr unit will do the heavy lifting for you and save you any number of headaches. While that’s fine as a general principle, it’s not the whole picture. There are cases when you might need Grid, even though your layout doesn’t require calc(). One example might be a fixed-width, two-dimensional layout, where each track is 200px wide – you don’t need calc() to tell you how wide those tracks should be, but you might still want the behaviour of Grid. Likewise, there are cases for using flexbox where you do need calc(), so this can only be interpreted as a guideline.