The profile of the camera depends on the light, the color of the iluminant.

The card should be used each time you change the illuminant.

The results would be different if you take it under a D65 light in controlled conditions, at the sun in a sunny day or in cloudy day or at sunset.

It may be even different under a sunny day in different months or at different places.

ISo setting may also affect color captured by the camera

So you should use it at the beginning of the session or even more if you change the light.