Supporter possession is a weird thing. Sometimes when a supporter comes on mid-game you feel the effect almost immediately other times its negligible. Anyway, although I like my teams to gain possession its not enough.

Its like most things in the game, in isolation the impact of any one thing is debatable/imperceptible. Its the interaction between orders, formations, player quailty, performance, possession and those lucky dice that makes things happen. Being good to your mum and showing kindness to animals also helps.