A seal and a signature have to be in the right place in the whole composition. If they are part of a longer inscription they also have to match it in style and fluency.
But seals and signatures are often carelessly compared out of the context of the composition. And to double up on this they are than compared to only reproduced reproductions in books or online, often taken from unknown sources and given and used without any idea where the reference was taken from. The image might be reproduced after a woodblock print or a doubtful reference, even a forgery. We simply do not know this.
So this means here is a little more care necessary, which reference material should be used. I use for Chinese painters for instance an edition publishing the seals including the paintings they are collected from.

In comparing the brush strokes and seal prints the material needs a consideration too. Not only that ink and seal color are taken on differently by different materials, the materials also will be affected in different ways by the mounting process, in old works this means several times. With silk you need to be much more careful than with paper.

So it would be a good appraoch to use signature and seal in the first hand only as a basic attribution that guides us where to look for references. We should check them again after the quality of composition, and the execution of the painting meets the expectations we have based on our references.
In inscriptions and calligraphy the general text should have greater value than the signature.
The seal should be valued even less.

The greatest imoportance always should lay on the investigation of the individual brushwork of the painting. To establish this as authentic we need good references, paintings by the same painter. These references should also fit in style and subject.