What is the best practice to apply the card design in webpage?

I have a question in terms of the card design style as I was designing the website for a company.

Basically, I noticed that other company's websites apply card design on their website. Like to display their "Key Features" or "Integration" or "Blog" in card design etc, but some just showing it in a flat style (without boxing). See examples below.

So my question is when or what is the best practice to apply the card design in webpage?

what if im designing a website that needs to show all those different sections, in which scenario i should apply card design style?

Thank you!