Apparently to avoid confusion next year, the FIA have announced the following revised flag system for all F1 races:
yellow light blinking every second – hazard on track, no overtaking
Yellow light turning orange once every three seconds – marshals on track, slow down and be prepared to stop
Yellow light blinking once every second, but twice every third time – slippery track, caution
Yellow light with small orange lights winking three times each second – race stopped
Orange and yellow striped light – safety car
Yellow and orange striped light – track clear, proceed at racing speeds
Orange light with yellow checks, winking two times a minute – lapped driver must allow a faster car past
Yellow light with orange checks – warning over driving standards
Light off – flag system failure. use your initiative.
More importantly – do they get even up to a second? These guys are flashing past these at a minimum of 180kph average. And in the case of restricting them from overtaking – obviously only works when another car is nearby and close enough to be overtaken. And they have to keep their eyes on these flag boards for 1-3 seconds?
Different colors is the way to go. Easily visible, slap bang and done.
Perhaps the FIA should experiment with different colours. Why limit it to green, yellow, red, blue and black? Why use confusing symbols and patterns that may be difficult to distinguish at speed or in low visibility weather? Why not purple flags for slippery track, orange for safety car, and brown for marshals on track?
(Of course, I realise every suggestion in the original post was some permutation of orange and yellow. Well done, @mazdachris!)