Hi,
How much time do you work to remove hair, strands of hair from around the head and other areas?

Below are examples of what I mean.
I work usually 30 minutes up to 2 hours when I receive requests like this.
Sometimes even more! it takes a lot of careful cloning and dodge and burn to recreate the background.
It's easier when the background is a plain color, but that's not often the case.
I'm talking about big images 25 - 40 megapixel, sensor grain must remain intact.

I would say about half an hour, but your right, it depends how much needs to be done and especially when you're trying to keep the same integrity, grain, and what should naturally blend with the original image vs adding too much fake grain/blurring/smoothing in the process etc.

It's not a hair ad, so not very long. Days if it's a hair ad.

I don't understand your sensor gain comment and why gain would apply to a cloning exercise... can you explain?

To replicate what you did might take me 10 minutes, if I did it the way I normally work, it might take as long as 30 minutes.

Robert, so good to see you again. You were missed.

OP
I take about the same amount of time as you but my work is non-commercial for family & friends only.

with wacom tablet i think image like this may take about 2h or more depending on the quality
cause you not just removing stray hairs also you can add some but first you have to ask what quality you need ? so you can plan alot of work or just improve your it ?

The question about hair retouching (which can be quite time consuming) should always be considered based on the purpose and budget. Images which need actual hair retouching are usually quite well styled, so then the post-processing work is not aimed at making something out of a total mess but rather to enhance what is already there. In such cases 10 hours per image can be fine because the end result is worth it. But in cases of simply shooting a girl in the park for fun that is not justified. It will be cheaper to redo the shoot with proper hair styling than trying to fix it in post. So it is better to explain that to the client and give him the option to save his money for a better hair stylist on his next shoot rather than rob him for retouching and deliver a result which will never be quite good regardless of the time spent. The possibilities of post-processing are almost unlimited but that doesn't mean every image deserves the time and attention.