Depends on the detail and size xD
Example.
This took me about... 10 - 12 hours total?
While this has taken me about 17 hours already, and still not done with it xD
I do it a few hours a day, try to get one stage done each day as well, like forming and shaping them, then baking them that night to have them harden, then paint the next day, then do touch ups and clear coat on the final day.
The second example has taken me longer to do cuz he's more complex and harder to keep together!!
But yeah, I try to have patience for a lot of things, luckily art is one of them xD