I use Lightroom 6.x and I usually start with a linear curve, adjusting the sliders in the "Basic" section accordingly. The section of the tone curve usually does not even open.
This is because I am not a professional and I never customize the point-by-point tone curve for a more precise tuning, therefore, I limit my question to the use of the predefined settings for the tone curve: linear, medium or high contrast.
I suppose one of the predefined tone curves should be chosen, even if they are placed visually lower, before retouching the remaining sliders, since it greatly affects the image (a finer adjustment is not within the scope of the question, it should always be applied later).
When is an approach with a linear curve, followed by an increase in contrast with the basic slider according to taste, preferred to the choice of a medium contrast curve, finally followed by a manual decrease?
What are the implications of the two approaches?
Edit: The statements about "professionals" were only my opinion. It is irrelevant to the actual content of the question.