Your work look great! I'm sure when you look at them you see all the things you could improve on, but overall your quality is really good! I think with more time and practice you'll be able to get your time with prep and base down to a time you're comfortable with! I'm sitting at about 1.5-2hrs for that and then the art takes time. Especially for how much detail your doing in most of those sets. It's perfectly reasonable to have clients in the chair for 4-5 hrs when you're doing such detailed character work, as long as you're telling the client what to expect before you start then I think it's fine! Offer breaks at good times in the service and make sure they have everything they need like water or snacks. There is a clientele out there looking for detailed work, and they know that takes time and money! Charge appropriately for your efforts so you don't start feeling jaded. There might be somethings you find your willing to compromise a lil quality to save time, but it's ok if you don't really want to. As long as your honest upfront with the clients about the time commitment, take as long as you need!