If I had air in my brake system could it effect my clutch pedal if they share the same reservoir?

[Tommy R]

If there is any air in the brake system will that effect my clutch pedal and if so in what way? Is it possible that it could make the clutch harder to press down? I asked because I know that in these cars the clutch system and the brake system share the same reservoir so to me That kinda makes sense but I'm not too sure .I have a manual 2006 Mustang GT and my clutch pedal is very stiff. For a while started to think that that was normal but now I'm not too sure. I asked a ford mechanic and he told me that that was a common problem with my car and I also took it to the dealership and had someone driving around the block with me, telling me that that was normal. So I started to think it was normal but now I'm not too sure Ive heard people say that these clutch pedals are supposed to be very light because they are hydraulic. But what also throws me off is that I'm met a smaller petite girl who owns the same year model as I do it's also manual and I asked her if her clutch felt stiff and she said it was very light and she said it was actually much lighter than she expected. I wasn't able to test it because I didn't know her and at the time I didn't have the time but I don't understand that. usually when ask this question I get from people that I need to work out more but I go to the gym every day so and I'm 26 so I'm pretty fit. I mean how much pressure should be required to press this pedal down all the way ? if I just put my foot on the pedal should the weight of my leg alone be a able to press it down because I definitely need more pressure than that and i weigh 225 so im not that light. I mean i basically have to put my back into it lol and to do it a few times is no big deal but in the course of driving it from traffic light to traffic light its gets old really fast. So if anybody has any info for me I would appreciate it. Thanks