When I do surveys of a fixed spot, I'll only count the highest number of individuals I see at one time. That way, if two robins show up, both leave, and one comes back, I'll have an accurate number and avoid double-counting.
When doing counts of a larger area (such as the coastal waterbird surveys), then I'll chose a path and count all the birds as I pass them. I'll count birds that fly from in front of me back to where I've already counted, but not birds flying from behind me into the survey area, because I might have counted them already, or will count them when I pass them later on. I also avoid walking back to areas I already counted.
For your robin surveys, you could try counting both side of the road at the same time while walking, or doing them separately and just taking the higher number.