making interesting drawings occupies few hours or even days of my time, because it's difficult to me to be concentrated, while drawing I often deflect.
I draw 1:1 with photoshop, pencil for base and other tools for effects. When floor to floor height isn't multiple of 3, I draw fragment in 3 or 4 pixels for each storey and then scale it vertically
for example animation of drawing process of
Annunciation Cathedral in Kharkiv, 2007
Ukraine hotel in Moscow, 2013