Its good to see you back, LFC Lloydy.
I've been thinking of it as: bigger pitch = harder to defend = more scoring.
More scoring is good for you if you think you're better than the teams visiting, and bad for you if you think you're worse than the teams visiting.
In some circumstances, you may think of this in terms of "In the games I care about", for example, as Rangers you might really only care about Celtic and your European opponents, assuming everything else is a win.
Note that that's not the only way to think of it. If I were expecting a ton of fixture congestion (
e.g., Championship team in the UEFA Cup), I might try a narrower pitch as I'd expect that to mean less running and more time spent with the ball out of play.