I am following English premier League and Australia A league. 80-85% matches 1st half Happen corner over 3.5 that's odds 1.32-1.40 . So anyone wants to safe betting then you can bet there. Not all matches. Select for a team like Manchester United. If Manchester United and it's partner fail to cover 3.5 corner in 1st half in a match then the next match stake high between Manchester United Vs opponent team. That's the simple tricks. This tips dose not work for 100%, so bet your own risk.
Your post is contradictory, because firstly you mentioned the strategy as a safe betting method, but on your last phrase you say this tip doesn't work 100%. It means the strategy may work or not, like any other we can make use of.
Anyway, it's an interesting concept that can be useful for some gamblers as a start point to develop their own betting patterns, by improving the one shared by you.