Consider if the blades and water flow pass obstructions like the dead wood, rudder or strut. When spinning if the upper and lower blades of a two blade propeller are both in time with (Close proximity) obstructions a "chatter" can develop in the drive line or rudder.
The grey or blue instances can be fine... a two bladed prop in a position such as the red hull could be a problem.
I will say if you only motor a little this would not likely be a problem but if you find your self motoring for days....