Well, the shovel and the pick, all together with texture, took me about ~30 minutes to create.
Other things like the lighthouse ~2-3hours. The caverns about ~7 hours I think, but that one is pretty complex. Even though you can copy 'n paste parts you still need to go thru all elements and check for seams and whether it intersects with other objects.
I rarely finish a model without taking a break though. I think it helps you to see errors you've made that before you wouldn't have been able to spot because you got so familiar with the image on your screen. See things (sometimes litterally) from a fresh perspective. I once finished a F15 jetfighter and I thought it was pretty much perfect, but the next day I looked at it I didn't like it at all; all the dimensions where incorrect, wings to small, landing gear to big etc.
Generally, the more complex a model is, the more time it costs. But also simpler models like character skins can consume a lot of time to create, but rather because it takes several tries to make it as close as possible to a real world creature. Also, with some objects that are very familiar might seem simple but they do have to be accurate to look real. I first got the blade of the shovel wrong and it just didn't look like a shovel at all. Took me several tries to get it right, and after I searched for some pictures on the web of shovels (yes, people put pictures of the weirdest things online, quite funny sometimes

).
I'm actually enjoying making models for Trespasser more than for other games because the polygon count is lower. Might sound strange but someday low polygon modeling will be an art of the past, as machines get faster and faster and can handle huge amounts of polygons...