It depends on the scene, number of figures, size etc, but of the dio's I have done recently, I find they don't add that much extra time to a build. Allowing for the time I put this aside, I reckon this took about 5 weeks. I get a lot of the dio done while I am waiting for paint to dry and things like that. When you start adding buildings and all the things like that, that's when it takes more time.
I have been doing dio's since my early days of modelling and I seem to be lucky in that I get a good feel for the layout. But even though I have a good idea of what I want the finished scene to look like, I allow the dio to evolve as I go along and don't stick rigidly to my original plan. At first, in this one the tank was going to be side on with all 5 crew members. But as it progresses and I can start to lay the actual model on the partially finished base, that's when I start to make the changes, but still sticking to the original idea.
I am a Norfolk man and i glory in being so
On the bench: Airfix 1/72nd Harrier GR.3/Fujimi 1/72nd Ju 87D-3