I find the best advantage to watching is to be able to avoid the pitfalls the game has set up for you, best example I can think of is where your player gets a yellow card and you change him and then his replacement gets a yellow card, you just know that the game had planned a red for you and if you weren't watching it would've happened, but at least you were able to keep 11 on the pitch and not play with 10, you wont know if the result was affected but easy to believe that 1 down with 10 men the good result is unlikely but if you snatch a draw with a slightly weakened 11 you can be happy that you probably avoided a defeat by attending and affecting