extra time=BS
when extra time begins in PES/WE-- no matter what the clock tells you-- each team has a limited number of "attacks" remaining, dependent on how long each possession lasts. the game simply cannot end w/ one team on the attack. similarly, the defense cannot end the attack (AKA possession) without touching the ball outside of their own third of the field, or clearing it really deep. Ever notice how when you break up an attack really deep into extra time, the game ALWAYS ends the instant you carry the ball beyond that invisible one-third line?
also, no matter how long the very first possession of extra time goes, there will always be at least one chance for the other side to attack. i have actually possessed the ball for 15 real mins to start extra time during a short game... and the defense still got to carry it all the way to the other end and take a couple corners b4 i carried it out of my 1/3 & finally ended the game.
for the most part, the more time on the clock the more change of possessions u can get. try this sometime: if you can get 5-6 mins of extra time on a low difficulty, stand in the neutral third of the field and continually lose and regain possession. you can "draw out" the whistle in ~10 seconds doing this. experimenting w/ this, i have found that if it says 2 mins added on the clock, it almost always takes exactly 4 of these quick change-of-possessions to draw a whistle. i have also found that the team trailing gets more leeway (essentially they get an extra chance to equalize)
i dont know the exact formula (time to possessions), but whatever it is the whole system is pretty stupid IMO. extra time should just be real extra time, not this BS "change-of-possession counting." its ridiculous that if you can hold the ball for 15 mins the game will continue.