When I did my shop, I was originally planning on running PVC lines for air. Then I read up on it and saw some of the pictures from people getting hurt when Schedule 40 PVC explodes. You never know when it will happen, or even if it will happen. What really scared me besides the possibility of loosing an eye is how common these things actually happen. It's not rare for them to explode, but fortunately most of the time, nobody is injured to the point that it gets reported. I just don't want to take that chance.
I was debating on whether to go with copper of steel pipe while building the shop, and in the end, found that having two hoses on the air compressor works perfectly. One line is 100 feet and goes through my wall to a garden hose hanger. It's rolled up outside and easy to use on anything out there. The other line is 50 feet and also on a garden hose hanger. Since my shop is only 24 x30, I can reach anything in there real easy with the hose that's just sitting there.
In the shops that I saw pipe used and wanted to copy, there were multiple connections all over the place for all the employees to use. That wasn't something that I had thought of. With just me working in the shop, one hose is never going to be in the way of others. In a commercial shop, you need those multiple connections because of everyone doing something different.
I realized that putting pipe in for air hoses wasn't something that I needed, and in three years of working in my shop, have found that I rarely use my indoor hose more then ten feet from where it's stored anyway.
Eddie