It's all about intent and artistic vision.

In studio lighting, for example, getting a perfectly white-balanced shot might be very important because the colors of your client's product need to be exactly right. You would never want to warm up (or cool down) their logo color, for example, in a product shot. Use the gray card to achieve correct white balance, and don't change it later.

On the other hand, when you're outside in the warm sunset light and want to shoot a portrait, getting "correct" white balance will remove that warmth. You want that red warmth because it's what makes the scene so special. In this case, you might use the gray card and as-shot white balance to remove an undesirable green tint, for example.

In another scene, your as-shot white balance might be pretty accurate. You shoot with the gray card, and in post decide the gray card's white balance is slightly better than the as-shot white balance. But, gee, it needs just a touch more red to be perfect so you adjust the temperature slightly.

It's all up to you.