Not much time, though if you count my daily check in here, I'm guessing 15 to 10 minutes a day.
As an X automobile painter, and model builder, I keep thinking I will have enough time and expertise to start doing custom painting and weathering on my large collection of 21stC toys eventually, but so far it's not happening. At least I can come here and admire other's work. Some who just blow me away with their knowledge and detail. Even watched the progress of some who were novices, turn into experts in a very short time, so it's encouraging.
My other hobby, being a guitarist in a rock band, has turned into my work, as it's the only thing I can get right now in this economy. Thank goodness I had the passion, or obsession to pursue getting good at it, so now it's the only thing keeping me alive...barely. So my hobby is my work now, though not my other passion of military models right now, as I'd like it to be
So 4 to 6 hours.